Ionite Fever

"Ionite Fever" is a special event that debuted in February 2020, and running for 20 days. In it, you can fight in a special event campaign in normal mode (unlike other special events, there is no heroic mode). For the official details, you can see the official post.

The event re-opened January 15, 2021, with an expanded shop. There were some issues with the units from the Lairs on release, but these are now fixed. The shop prices were adjusted January 20. In the initial release of the event, it was called "Ionite Pyrexia", but the 2021 release updated it to "Ionite Fever". The difficulty of some levels was also adjusted relative to the 2020 version.

In 2022, the event was again available from January 24 to February 9, 2022. There were no changes from the 2021 version; however, enemy Psionics do not seem to be functioning correctly, which makes many maps significantly easier. The event returned in 2023 from January 25 to February 15 and once again from September 28 to October 18 (starting before previous event, Knowledge Day, ended - likely on accident), again with no changes from the 2022 version.

## Campaign

The campaign contains a total of 20 areas, organized into 5 branches originating from the area in the bottom right. The first area, in the bottom right, can be unlocked for free. The rest of the areas must be unlocked by using event resources: either raw ionite ore (for the four side branches) or shabby maps (for the central branch). You can unlock the areas in any order. Once you win a fight in an area, that area will go on cooldown for a length of time. The resources required to unlock an area, as well as that area's cooldown timer, increase as you move deeper into the campaign map. With the exception of the last map, you win in the normal way, either by capturing the enemy spawn point or destroying all units. On the last map in the center branch, there is a boss with 600,000 HP that must be destroyed. It is similar to a convoy boss, but unlike convoy bosses, this one does not attack.

Note that in the table below, the enemy levels listed contain two parts: the first number or range is for units spawned from the enemy spawn point, and the second number is for units spawned from enemy lairs. For more information see the detailed level information section below. Most levels also have a standard troop loadout of 5I, 5St, 2HI, 1Sp, 2V, with a few exceptions:

* "Snoridge" Mine is 5I, 4St, 2HI, 1Sp, 1V
* Altar of Science is 7I, 6St, 3HI, 1Sp, 2V
* The echo of the past is 7I, 6St, 3HI, 2Sp, 1V
* Scientific secrets is 7I, 7St, 3HI, 2Sp, 2V

Note that for the last three, the loadout is large enough that it extends onto a second page -- make sure that you check this so that you don't end up using autofilled units you didn't mean to use! In "Scientific secrets", you must also take a minimum of 10 units (like a convoy battle).

## Event resources

There are five different resources that can be obtained during the course of the event.

Raw ionite ore is given as a reward for winning battles on the four side branches. It is used to unlock maps on the four side branches, and to purchase some items from the event shop. Areas that are unlocked with raw ionite ore can also be unlocked with gold at a rate of 25 gold per raw ionite ore. At the shop, you can exchange 10 raw ionite ore for 1 purified ionite.

Shabby maps are given as a reward for winning battles on the end areas of the four side branches. They are used to unlock maps on the central branch, as well as to run the last two maps on the central branch. In the initial release, they were also required to unlock some items in the shop, but this was removed in the 2021 update. Areas that are unlocked with shabby maps can also be unlocked with gold at a rate of 250 gold per shabby map. Alternatively, shabby maps can be purchased from the event shop for either 5x isolated infected ionite or 100 gold.

Purified ionite is given as a reward for winning battles on the central branch. It is used to purchase higher-level items from the event shop. Purified ionite can also be purchased from the event shop for 10x raw ionite ore, or conversely used to purchase isolated infected ionite.

Isolated infected ionite is given as a resource for winning the last three battles on the central branch. It is used to purchase items from the event shop. Isolated infected ionite can also be purchased from the event shop for 10x purified ionite, and 5 isolated infected ionite can be traded for a shabby map.

Ionite Trophies determine your final rating in the event. When you win a battle, you get one trophy for each enemy unit and building killed. At the end of the event, you receive additional rewards depending on your total rating accumulated.

## Enemy units and buildings

There are four enemy units that you will face:

* Enslaved miners are the enemy infantry unit. They appear in groups of 6, and can very quickly swarm your position. Because they are melee fighters, they can easily capture your spawn point if it is not well defended. At higher levels they have substantial evasion, making them quite difficult to quickly take down.
* Resurrected miners are the enemy stormtroopers. They are not quite as fast as the enslaved minors, and only appear in groups of 3, making them somewhat less of a threat.
* Juggernauts are the enemy heavy infantry. They are slow and only appear singly, so they are not too dangerous as an offensive unit, but their ability to absorb large amounts of damage makes them very effective as a screen for more dangerous units.
* Psionics are the enemy special unit. They use psionic ability to attack, producing an effect similar to a discharge. At lower levels they are not too dangerous, but at higher levels they become extremely deadly, as their damage is high enough that they can easily incinerate an entire squad of your infantry or stormtroopers in a single shot. Starting from 2022 event version, psionics summoned by lairs are bugged and instead use non-AoE ranged attack, which still is damaging but far less dangerous; psionics coming from enemy spawn are still working properly.

In addition, there are three special enemy buildings that will appear on most maps:

* Lairs summon enemy troops approximately every 11 seconds. The troops summoned are randomly selected from the four types available. The level of the troops summoned is equal to the level of the lair. All lairs on the map are synchronized and will summon troops at the same time. The event maps are designed to use lairs to either overwhelm you with weaker versions of the normal troops or to quickly capture your spawn point.

* Psionic beacons cast fear on all nearby units every 16-18 seconds. This effect is the same produced by the "Lord of the lands" Berserk skin or Esben Defender in his transformed form. While afraid, your units will usually run backwards towards your spawn, but occasionally sometimes run deeper into the level. As psionic beacons effectively push your army back, the event maps are designed to use this effect to clump your units together (to make you vulnerable to the psionic unit's discharge attack) or to protect other event buildings when they're placed nearby. Psionic beacons do not have any level.

* Enslavers take control of one nearby squad, similarly to the effect of Betrayal, every 20 seconds. This causes the affected unit to act like an enemy; they will run towards your spawn and will target your units. Your other units will target the affected units and try to kill them. The effect wears off after 7 seconds. The Enslaver can target units slightly further away than the Infantryman default range. Long-range units are recommended to safely destroy the Enslaver. Enslavers always seem to have level 1.

## Event shop

The items available in the shop are as follows. In the initial 2020 release of the event, shabby maps were required to unlock many of the more powerful store items, but this was thankfully removed in the 2021 appearance.

## End of event rewards

Rewards are given at the end of the event based on your total accumulated rating . Your rewards increase gradually with each level of rating points you achieve, with higher rewards being unlocked starting at higher levels of rating.

The rewards are:

* Res.: the specified quantity of each basic resource (////)
* Man.: the specified quantity of each type of manual (health/damage/accuracy/evasion/armor/skill)
* Units: the specified quantity of each of Elite Enslaved miner, Elite Resurrected miner, Elite Juggernaut, Elite Psionic
* SP: spare parts
* SRK: the first column is the specified quantity of SRK Mk.I, SRK Mk.II, and SRK Mk.III, and the second column is the specified quantity of SRK Mk.IV and SRK Mk.V
* MRK: as above, for MRKs
* UIC: unstable ionite cores
* Mod: ordinary equipment modifier modules

## Detailed map information

In all the listings below, the "enemy units" lists the troops that emerge from the enemy spawn point, not including troops that the Lairs in the level may create. Note that with the exception of the last level, there are no strategic points in any of the missions.

### Entrance chamber

 **Tips** | * This map is shaped like an N. The enemy spawn is in the top right; your spawn is in the bottom left. At each bend is a lair and there is a psionic beacon in the middle.
* Enemies will try to swarm you at the start of the level and the psionic beacon will try to keep you there. The first lair is positioned so that melee troops may run past your hero unless killed or blocked by other units.
* You can push through either by exhausting enemy reinforcements, with enough troops or with a strong enough hero.

### Left branch

 **Tips** | * This map is shaped like an N. The enemy spawn is in the bottom left; your spawn is in the top right. At each bend is a psionic beacon.
* This map is much easier than the "Snoridge" Mine. With only one spawn point, the enemies can eventually be exhausted and they're usually lined up to be blocked by your hero without needing other units.
* Keep an eye on your hero's HP if they focus fire on the first beacon, but don't have enough damage to kill it quickly.

 **Tips** | * This map is shaped like an O. The enemy spawn is at the center left; your spawn is at the center right. On the opposite side of the terrain from your spawn are 2 enslavers and behind those are 2 lairs.
* Enemies will split around the central barrier and try to force you to split your forces. Your hero will tend to go around the bottom and the higher level enemies (the ones coming from their spawn point) will tend to go around the top. The enslavers will be able to target your units as they reach the opposite side of the central barrier.
* If you have troops strong enough to tank the enemy for a bit, one way to deal with the enslavers is to only send one unit around the top and one around the bottom. This will limit the amount of infighting your units do since they'll mostly run back towards your spawn while they're enslaved. Units with range upgrades can also take out the enslavers from near your spawn point.

 **Tips** | * This map is shaped like a Y. The enemy spawn is at the center top; your spawn is at the center bottom. There are 2 enslavers on the left and right sides of the choke point and 2 lairs at the tips of the Y.
* This battle is considerably harder than the others unlocked for 15 or less raw ionite ore. The enslavers will tie up your forces while enemies pile on you from the top of the map. If two of your units are enslaved at the same time, they may gang up on your hero and burn down their HP quickly.
* A good strategy is to either focus on taking down one of the enslavers, or to use long-range troops to attack them from outside of their range. If you can't outrange the enslavers, try to make sure they entrap a unit with either low range or low damage. Watch out for the trickle of new psionic enemies, as even at level 5 they do 300+ damage and are effective for defending this level's choke point.

 **Tips** | * This map is shaped like a mushroom. The enemy spawn is at the center top, in the cap; your spawn is at the bottom center, in the stem. On either side of the stem is an Enslaver. On the left and right sides of the cap is a Lair.
* Brick and the Psionic enemies will chip away at your HP while melee enemies and the Enslavers try to keep you pinned near your start. The path to each Enslaver points up towards the top of the map, so it will be difficult for short range units to approach. Infantry with +5 range or more can shoot the Enslavers safely from the sides of the stem near your spawn.
* This map is very difficult without long range units or increased range infantry. There is a brief period before Brick gets within range and the Lairs start spawning which will allow you to take out the Enslavers early. Try not to let the enemy psionics pile up, since their damage is very high. Stormtroopers (4 man or less) and heavy infantry can fit between the two Enslavers without triggering them, as long as their pathing doesn't deviate from the centerline. Infantry squads, on the other hand, may be too wide.

### Right branch

 **Tips** | * This map is shaped like an S. The enemy spawn is in the top right; your spawn is in the bottom left. At the first bend is a Psionic Beacon, at the last is an Enslaver, and there are 2 lairs at either end of the center line.
* This map is easier than "Snoridge" Mine, but slightly harder than Underground Threat. With two lairs, the enemy will attempt to swarm you at the start and keep you there with the Psionic Beacon. The first Lair is positioned so that melee troops may run past your hero unless killed or blocked by other units. The Enslaver won't target you until you get close to the second bend.

 **Tips** | * This map is has a loop around a central barrier in the upper half and two branches in the lower half. The enemy spawn is at the center top; your spawn is at the center. There are 2 psionic beacons on the left and right sides of the central barrier and 2 Lairs at the ends of the lower branches.
* With the 2 Lairs, the enemy will try to quickly capture your spawn point while your forces are tied up by the Psionic Beacons. Your hero tends to go around the right side of the central barrier, while the enemy forces from the top (their spawn point) tend to go around the left.
* It's helpful to immediately send a fast unit, like a Stormtrooper unit, to try and destroy at least one the Lairs in the lower branches. If your hero has long enough range, they can also take out the lairs from near your spawn point. While blocking enemy troops from the top left, try to destroy the other Lair. Once those are gone, you can focus your attention to the enemy troops coming from the top of the map.

 **Tips** | * This map is shaped like two chevrons or Vs. The enemy spawn is at the end of the top left branch; your spawn is at the center bottom. There is 1 Lair at the end of each of the other chevron branches.
* With the 2 Lairs in the lower branches, the enemy will try to quickly capture your spawn point while your forces are tied up by enemy troops coming from the top of the map. The lower branches are much more likely to capture your spawn point due to the choke point between the top of the map and your spawn.
* It's helpful to immediately send a fast unit, like a Stormtrooper unit, to try and destroy at least one the Lairs in the lower branches. Watch out for the trickle of new Psionic enemies as even at level 5 they do 300+ damage and are effective for defending this level's choke point.

 **Tips** | * This map is shaped like a dumbbell. The enemy spawn is at the top left; your spawn is at the bottom right. On the enemy's side of the choke point, there is an Enslaver with a Lair on either side.
* Enemies and their hero will pour through the choke point to try and overwhelm you while the Enslaver hinders your efforts to move forward. The enemy hero, Klausbot, can deal a lot of damage to your army with his AOE melee attack. The longer it takes to fight Klausbot and the melee units, the more Psionic units will pile up on the other side of the choke point to melt your army as they fight the Enslaver.
* The two main challenges for this map are Klausbot and the enslaver. It helps to kill Klausbot quickly to limit how much damage he can do. On this map, the Enslaver will often pick targets incorrectly (such as your hero or enemy units) because they're all in close proximity inside the choke point.

### Center-left branch

 **Tips** | * This map is an open field. The enemy spawn is at the top right; your spawn is in the bottom left. There are 2 lairs along the top and 2 more along the right side.
* With four lairs, the enemy will try to swarm and quickly capture your spawn point. Because spawned enemies will run directly at your spawn point, this also means that you can rush the enemy spawn with low range or melee units, such as lycanthropes.
* Keep an eye on your spawn point; you may need to send units both up and right to make sure that you are blocking the melee enemies.

 **Tips** | * This map is shaped like an arrowhead. The enemy spawn is at the top left; your spawn is at bottom right. There are 2 lairs, one in the top right and one in the bottom left. There are 2 psionic beacons, one along the top and one along the left side of the map.
* The map effectively funnels enemy units to the choke point near your spawn to try and overwhelm you. The lairs are protected by the psionic beacons, which will scare away your units if they don't have enough range.
* It's helpful to immediately send units to try and destroy at least one of the lairs. They will also effectively block enemy units coming from that direction and will take out the nearby psionic beacon afterwards.

 **Tips** | * This map is an open field. The enemy spawn is at the top center; your spawn is at the bottom center. There is one lair on the middle of the left side and one lair on the middle of the right side.
* The enemies that spawn from the lairs will try to capture your spawn point quickly and they won't be blocked by any units that you send up towards the enemy spawn.
* The lairs on the sides need to be killed quickly to protect your spawn point. When sending units, try to send them diagonally away from spawn, or even along the bottom edge of the map as clicking on the lairs tends to send units straight upwards, where they get caught on enemies coming down from the top of the map. If you don't have armor piercing to deal with Elsa quickly, keep a few units in reserve so that you can kill new enemies that spawn from the top of the map (like you would in a convoy).

### Center-right branch

 **Tips** | * This map is shaped like a horseshoe. The enemy spawn is at the bottom left; your spawn is at the bottom right. There is one lair in each of the top corners and a psionic beacon between them.
* With two lairs, the enemy will attempt to swarm you at the start and keep you there with the psionic beacon. The first lair is positioned so that melee troops may run past your hero unless killed or blocked by other units, especially because your hero walks left (directly towards the enemy spawn) at the start of the battle.
* Since the first lair is located before the psionic beacon, you can rush to destroy it before too many enemies arrive, making the rest of the battle easier.

 **Tips** | * This map is an open field. The enemy spawn is at the bottom right; your spawn is at the center. There is a lair in each of the other three corners.
* You start this battle surrounded by enemies and they will try to capture your spawn point quickly.
* Try to focus fire one of the lairs quickly. Since the lairs may randomly spawn fast melee units at you, try to save a few action points so that you can quickly deploy units to block that direction (if you click on the lair in the corner, your units will walk out in the correct direction to block effectively).

 **Tips** | * This map is shaped like a ring. The enemy spawn is at the center right; your spawn is at the bottom left. There is a lair in the top right and bottom right corners. There is a psionic beacon in the top left corner and on the bottom side of the ring.
* You start this battle pinned into the bottom left corner by the psionic beacons. All of the enemies and their hero will come down the right side and along the bottom. If you get bogged down fighting melee units for too long, the enemy Psionics will pile up and burn down your army.
* It's helpful to send a portion of your army up to the top-left psionic beacon to try and cap the enemy spawn point. It may take some time as shorter ranged units, like stormtroopers, will get scared and longer range units may target the melee units coming along the bottom of the ring.

### Center branch

 **Tips** | * This map is an open field. The enemy spawn is at the bottom right; your spawn is at the top right. On the left side of the map, there are 6 Lairs arranged in a zigzag from top to bottom.
* With 6 Lairs, the enemy will try to overwhelm and capture your spawn point. Your hero will walk down, directly towards the enemy spawn point, making it harder for them to defend your spawn point as the battle goes on. Here are the directions that enemies from each Lair can approach your spawn point from enemies: NW (1st Lair), W (1st, 2nd and 3rd Lairs), SW (3rd, 4th, 5th and 6th Lairs) and S (spawn point only).
* Lairs have to wait their full recharge time before they spawn their first units, which gives you a chance to approach and try to kill a few. Try to keep a few action points available for when the Lairs are about to spawn. In order to block enemies at spawn, you may need to deploy units in the North West, West, South West and South directions to cover all the angles they might approach from.

 **Tips** | * This map is an open field. The enemy spawn is on the right side; your spawn is on the left side. There is a lair in each corner.
* With the 2 lairs on the left side, the enemy will try to quickly capture your spawn point. With the two on the right side, they will try to slow your progress towards capturing their spawn point. Your hero will walk towards the right, directly towards the enemy spawn.
* Since two of the lairs are so close to your spawn, protecting your spawn point and killing them should be the top priority, as either lair can spawn the fast enslaved miner squad which will reach your spawn in only a few seconds.

 **Tips** | * This map is shaped like a diamond and is very large; there are branches off each side and a central area that opens into the diamond path at the top left and top right. The enemy spawn is at the top center; your spawn is at bottom center. There are 4 lairs in the center area and one lair in each of the branches. The branches at the bottom have 1 psionic beacon each. The branches at the top have 1 enslaver each.
* With 8 lairs, the enemy will flood you at your spawn point. The enemies coming from the top of the map (both from the spawn point and the central area) tend to approach from the left side. Your hero tends to go around the right side. The 4 lairs in the middle can be shot by unskinned infantry without entering the center area. The enslavers and psionic beacons are not quite close enough to the middle path to target you unless you move into the branch they're located in.
* Fast units, such as Bloodletter, Marauders, or Elite Enslaved miner, can run around the right side of the map with limited resistance; but if they're caught they might die. When deploying troops to block your spawn point, to align your units so that enemies are less likely to run past, it may help to click on the Lair in the lower left or lower right. There is enough time to deploy about 5 action points worth of units before the first waves approach your spawn.

 **Tips** | * This map is shaped like a diamond and is very large. The enemy spawn is on the left corner; your spawn is on the right corner. On each side of the diamond is an alcove with 2 lairs and 1 Psionic Beacon each.
* Due to the large number of lairs, you will quickly be swarmed by large numbers of enemies. While your army fights melee units, Psionic units will pile up and snipe you. If your hero goes off on their own, they may get stuck fighting enemies, depending on their attack range. Due to the psionic beacons, it's difficult to kill any of the lairs unless long range troops are used.
* Enemies from their spawn point tend to run over the top half of the diamond. Your hero tends to run under the bottom half of the diamond. There is enough time to deploy about 5 action points worth of units before the first waves approach your spawn.

 **Tips** | * This map has 4 branching paths. The enemy spawn and boss are at the end of the center branch; your spawn is at the bottom left. In addition to the enemy buildings, this map has several regular capture points. The left branch has a victorious courage. The right branch has a psionic beacon, a lair and a mortar. The center-right branch has a psionic beacon, a lair and a victorious courage. The center branch has a field healing. There is a small path that connects the center and center right branches, near the enemy spawn point.
* Similar to convoys, you need to kill the boss to win and you don't lose if your hero dies. Unlike convoys, but like other event maps, the enemy's spawn point can be exhausted. The lairs will continue to spawn units endlessly until either the boss is killed or you lose, so it's advised to destroy them. Each lair is guarded by a psionic beacon. Certain buildings/capture points have high priority on this map, which makes navigating it confusing. For example, units may not advance past the field healing until the victorious courage on the left is captured (they'll instead run back to get it), so it's advised to capture that early in the battle to avoid pathing issues.
* Other than the wonky pathfinding, there are a few challenges to contend with. The enemies coming their spawn are max level (except Psionics) and will soak a lot of damage. While blocking the melee units, the Psionic enemies (extremely powerful even at lvl 11) can easily 1-2 shot your basic infantry and stormtroopers. Another challenge is killing the boss within the time limit. It doesn't attack, but it has high armor. To deal with these challenges, it may help to use a Scout and few high damage units or premium units. Note also that melee units coming from the enemy spawn will approach your spawn point from the NE, but when you deploy units, they will usually come out the N (top capture point) or E (most other destinations) directions. To send blockers out to the NE, click near the cliff face near spawn.