Frost Moon

Not to be confused with the Frost Legion, another summoned event.
 *"The Frost Moon is rising..."*

The **Frost Moon** is a Hardmode, post-Plantera, Christmas-themed event summoned with the Naughty Present at any time at night, ending at dawn (4:30 AM). It can be summoned at any time of the year and does not require the actual Christmas season. During the event, unique and highly difficult enemies spawn at high rates and attack the player. It is similar to the Pumpkin Moon event, but consists of more waves and includes slightly more content. Visually, the moon turns into a snowman head, though remaining in its current phase.

The entire event consists of 15 waves, plus 5 "bonus waves". Waves progress as the player reaches certain kill scores (though kill scores are not displayed to the player before wave 20). After a wave's required score is met, the next wave begins, and the kill score is reset to 0. Status messages will indicate when the wave has advanced, and which wave has been achieved. See the table below for the points awarded for each enemy and the score required for each wave.

The Frost Moon event always ends at 4:30 AM. The goal of the event is to progress through all 20 waves *before* the event ends, although the  achievement for the event is awarded at wave 15.

The Naughty Present, which summons the Frost Moon, requires materials only available in Hardmode worlds where the player has already defeated Plantera (although it can still be summoned in pre-Hardmode worlds). As such, it is intended to present a challenge even to players with the best possible equipment. In the final waves, multiple boss-level enemies are fought at once.

Frost Moon enemies drop powerful weapons, as well as pet and vanity items. Most drop with extreme rarity, and even players who manage to complete the event will find they need to do so several times before obtaining them. Drop chances for items dropped by bosses increase as waves are completed. See the section below for a more detailed description of the rates at which loot and trophies drop.

Reaching wave  15 /  20 before 4:30 AM will display the message “The spirit of Christmas spreads cheer...” at dawn (4:30 AM). For the entire day and night, all special effects of the Christmas season will occur. At 4:30 AM of the next day, the message “The spirit of Christmas fades...” will appear and all Christmas events will no longer occur until the Christmas season begins again or the player reaches the 15th wave of the Frost Moon again.

## Contents

Characters
* ​Present Mimic
* ​Flocko
* ​Gingerbread Man
* ​Zombie Elf
* ​Elf Archer
* ​Nutcracker
* ​Yeti
* ​Elf Copter
* ​Krampus
* ​Everscream(boss)
* ​Santa-NK1(boss)
* ​Ice Queen(boss)

Unique DropsFrom Zombie Elf:
* ​Elf set

From Everscream:
* ​Christmas Tree Sword
* ​Razorpine
* ​Festive Wings
* ​Christmas Hook
* ​Everscream Trophy
* ​Everscream Relic(Master Mode only)
* ​Shrub Star(Master Mode only)

From Santa-NK1:
* ​Elf Melter
* ​Chain Gun
* ​Santa-NK1 Trophy
* ​Santa-NK1 Relic(Master Mode only)
* ​Toy Tank(Master Mode only)

From Ice Queen:
* ​Blizzard Staff
* ​North Pole
* ​Snowman Cannon
* ​Baby Grinch's Mischief Whistle
* ​Reindeer Bells
* ​Ice Queen Trophy
* ​Ice Queen Relic(Master Mode only)
* ​Frozen Crown(Master Mode only)

Music
* ​Frost Moon
* ​Invasion (Otherworldly)

## Waves

* Total points required to reach wave 15: 3410, wave 20: 10160
* Present Mimics may spawn at any wave, instead of wave-appropriate enemies, if there are currently less than four Present Mimics around.
* The maximum number of bosses at once depends on the wave. While this number is reached (or possibly exceeded, for example if the player manages to somehow reach wave 9 without killing two Everscreams from wave 6), no more of this type of boss will spawn.

### Loot

* All of the boss-type enemies (Ice Queen, Santa-NK1 and Everscream) have increased chances to drop loot in later waves. This chance starts at 10% (20%) in wave 4, and grows at a nonlinear increasing rate up to 16.67% (100%) by wave 15, continuing to 25% (100%) by wave 20.
	+ The above chance *does* affect trophies on PC, Console, Mobile, and tModLoader; it does not affect them on Old-gen console, Windows Phone, Old Chinese, 3DS, and tModLoader Legacy.
	+ The exact formula for the drop chance is as follows:

	with W = current wave number (plus 7 if in Expert), and
	with E = 0 or 2.
	This chance is affected by luck.
* In all versions, trophies have their own, separate chance to drop (which, on PC, Console, Mobile, and tModLoader, *also applies* alongside the general drop chance, as explained above). Starting at wave 15 (or, on Old Chinese and tModLoader Legacy, at wave 8 in Expert Mode), there is a chance each Ice Queen, Santa-NK1 and Everscream killed will drop its respective trophy. This chance increases at wave 17, and again at wave 19; on Old Chinese and tModLoader Legacy in Expert Mode, these increases instead happen at wave 10 and at wave 12, respectively. On PC, Console, Mobile, and tModLoader, Luck does *not* affect this chance. The trophy drop rates for each version in each wave are shown in the table below.

## Notes

* The Frost Moon event will sometimes end after leaving and then reentering the world.
* On the Old Chinese version and tModLoader 1.3-Legacy version, Everscream, Santa-NK1 and Ice Queen can drop their trophies as early as wave 8 in Expert Mode.
* Water Candles, Peace Candle, Battle Potions and Calming Potions have no effect during the invasion, as the same with some other events.
* If the player is killed during the event, the event is not canceled. The player will keep re-spawning and can continue fighting its enemies as the event continues until dawn. In single-player games, exiting the world and reloading it will cancel the event, but it will also delete the items from the ground.
* The Frost Moon does not stack with the Blood Moon. Summoning the Frost Moon while a Blood Moon is active will result in a regular Frost Moon.
* Summoning a Pirate Invasion during a Frost Moon will cancel it.
* Any boss enemies that are still on a player's screen by the time dawn breaks will begin to move rapidly in a single direction, rushing off-screen to despawn. It is still possible to pursue or even kill some bosses while this is occurring.
* Lingering enemies beaten after the event is over will never drop any rare items.

## Achievement

 **Ice Scream** • *“Reach the 15th wave of a frost moon, where the festive season quickly degrades into madness.”*Reach the 15th wave of a **Frost Moon**. Category:  Slayer
## Tips

For more elaborate strategies on defeating Frost Moon, including weapon and arena recommendations, see Guide:Frost Moon strategies.
* Because spawn rates for areas where Frost Moon enemies cannot spawn are also increased, a Frost Moon can be used to farm for other items, e.g., Pirate Maps at the Ocean, while completely avoiding the Frost Moon enemies.
* The Frost Moon enemies are susceptible to the Ichor debuff, which makes a Flask of Ichor, Ichor Arrows or Bullets, or the Golden Shower very effective.
* Players should kill the enemies as soon as they spawn to ensure that more enemies can spawn continuously in order to increase the chances of reaching later waves.
* The Frost Moon can be a great way to obtain a large amount of coins quickly.
* A good potion to use is the Warmth Potion as it decreases damage significantly from enemies in the event.

## Trivia

* On the Old-gen console version, Windows Phone version, and Nintendo 3DSversion, the Frost Moon is often considered the hardest event in the game.
	+ The Lunar Events, which are not available on those versions, are substantially more difficult.
* This is one of the few post-1.2 features available on the Nintendo 3DSversion.
* The soundtrack for the Frost Moon strongly resembles and was potentially inspired by the Trans-Siberian Orchestra, a Winter/Christmas themed rock band.
* Unlike its Halloween-themed counterpart, Pumpkin Moon, this event does not drop a summon weapon.

## History

PC version
* Desktop 1.4.1: Requirement to unlock one in-game day of Christmas changed to Wave 15.

* Desktop 1.4.0.1: Reaching the end of the Frost Moon unlocks one in-game day of Christmas.

* Desktop 1.3.0.4: Fixed invasion progress wrapping around to -32768 when exceeding 32767 points in multiplayer.

* Desktop 1.3.0.1:
	+ Added Elf Archer Banner, Elf Copter Banner, Flocko Banner, Gingerbread Man Banner, Krampus Banner, Nutcracker Banner, Present Mimic Banner, Yeti Banner, and Zombie Elf Banner.
	+ Frost Moon points for defeating Flocko and Krampus both reduced to 0.

* Desktop 1.2.4.1:
	+ Elf vanity now drops from Zombie Elves during a Frost Moon.
	+ Fixed bug where Frost Moon waves 14 to 19 had "Santank" instead of "Santa-NK1" for the name.

* Desktop 1.2.4: Verify Frost Moon points for defeating Krampus increased from 8 to 10.

* Desktop 1.2.3.1:
	+ Made it slightly easier to advance in Frost Moon waves.
	+ Made several Frost Moon monsters shoot slower and do less damage.

* Desktop 1.2.3:
	+ Pumpkin Moon and Frost Moon can now be started when using a Snowman pet.
	+ All waves in Frost Moon correctly use "Flocko" in the warning.
	+ Flocko & Elf Copter now both correctly run away at dawn.
	+ Fixed frost moon wave display text (Elf Zombie to Zombie Elf).

* Desktop 1.2.2: Introduced.

Console version
* Console 1.05: Introduced.

Nintendo Switch version
* Switch 1.0.711.6: Introduced.

Mobile version
* Mobile 1.4.0.5.0: Reaching the end of the Frost Moon unlocks one in-game day of Christmas.

* Mobile 1.2.11212: Introduced.

Nintendo 3DSversion
* 3DS 1.03: Introduced.

## References

1. ↑ 1.0 1.1 1.2 Information taken from the PC 1.4.2.1 source code, method `CheckProgressFrostMoon()` in `Terraria.NPC.cs`. There may be inaccuracies, as the current  PC version is 1.4.4.9.
2. ↑ Information taken from the PC 1.4.2.1 source code, method `CheckForMoonEventsStartingTemporarySeasons()` in `Terraria.Main.cs`. There may be inaccuracies, as the current  PC version is 1.4.4.9.
3. ↑ Information taken from the PC 1.4.0.5 source code, method `SpawnNPC()` in `Terraria.NPC.cs`. There may be inaccuracies, as the current  PC version is 1.4.4.9.
4. ↑ 4.0 4.1 4.2 Information taken from the PC 1.4.0.5 source code, method ``RegisterBoss_FrostMoon()`` in ``Terraria.GameContent.ItemDropRules.ItemDropDatabase.cs`` and class ``FrostMoonDropGatingChance`` in ``Terraria.GameContent.ItemDropRules.Conditions.cs`` There may be inaccuracies, as the current  PC version is 1.4.4.9.
5. ↑ For trophies, Expert Mode has a ~~33.33\*~~1/3 (33.33%) chance of reducing the denominator by 1 compared to Classic Mode; e.g. in Expert Mode on wave 15 on PC, Console, Mobile, and tModLoader (or on wave 8 on Old Chinese and tModLoader Legacy), there is a 2/3 chance that the drop rate will be ~~25\*~~1/4 (25%) (25%), but a 1/3 chance that the drop rate will be ~~33.33\*~~1/3 (33.33%); thus, the average of these outcomes is  ≈ 27.27%; this does not take into account the overall item drop chance. Information taken from the PC 1.4.0.5 source code, method ``RegisterBoss_FrostMoon()`` in ``Terraria.GameContent.ItemDropRules.ItemDropDatabase.cs`` and class ``FrostMoonDropGateForTrophies`` in ``Terraria.GameContent.ItemDropRules.Conditions.cs`` There may be inaccuracies, as the current  PC version is 1.4.4.9.