Eidolon Hydrolyst

The Eidolon Hydrolyst is a titanic spectral Sentient Eidolon creature that can be summoned on the Plains of Eidolon at night, acting as one of the Grand Bosses of the landscape. This is the third and final of the 3 night bosses of Plains of Eidolon, preceded by Eidolon Teralyst and Eidolon Gantulyst. This one is large enough to wield the landing strut of an ancient spacecraft as a weapon, and its arcane energies create localized storm systems wherever it surfaces.
All Eidolons are remnants of a Sentient that was defeated in a battle against the Tenno during the Old War, whose remains now wander the plains perpetually searching for their lost components. These fragments are, however, still formidable creatures armed with powerful attacks and near-impenetrable defenses, and are hostile to both Tenno and Grineer alike.
It is important to note players that have not unlocked Transference from The War Within won't have any means to properly fight the Eidolon Hydrolyst. 
==Behavior==
After Tenno capture the Eidolon Gantulyst, they must offer their Radiant Eidolon Shards on the Eidolon shrine located in the middle of Gara Toht Lake. This will cause the Eidolon Hydrolyst to emerge from the lake, marked by a column of green light.
The Hydrolyst generally walk in one direction, even if the Tenno are nearby, though their attention can be drawn to specific locations by using Eidolon Lures found throughout the Plains at night. The Hydrolyst has many different attacks which do extremely high damage, and while most of those attacks are telegraphed, they may remain quite hard to dodge, even with extensive use of the Operator's Void Mode. Like the preceding Gantulyst, the Hydrolyst is unusually mobile for its sheer size.
*Enhanced Seeking Projectiles: A sphere of light emitted from the Hydrolyst's back which splits into multiple homing projectiles. These are more accurate than the Teralyst's, and are harder to avoid.
*Ground Stomp: Stomps the ground, sending out a ground shockwave that knockbacks back any Tenno in its path a great distance (100 meter radius). 
*Ground Smash: Smashes the ground, sending out a series of high-damaging, homing quakes to the Tenno's position. These homing quakes can stun the Tenno and are 25m high. These quakes do not return to the Hydrolyst's position, and instead disappear at their stopping point and spawn green bubbles in the air that will slowly float up and grow in size, though they can be shot down using amps. Failing to shoot down these bubbles in time will cause them to detonate, dealing a considerable amount of magnetic damage with a guaranteed magnetic proc in a large area.
*Gun Swing: Swings its gun arm while firing it in a wide arc, each bullet creating a 2m wide explosion.
*Summoning Scream: The Hydrolyst glows green and screeches into the air. This will summon and buff Vomvalysts around it, also sending Red Orbs to nearby Vomvalysts, making them a Red Glowing variant armed with an Opticor-like beam that is fired in a cone shape that deals immense damage to Operators and Warframes alike after aiming.
*Regenerating Scream: The Hydrolyst glows green and screeches. This will cause surrounding Vomvalysts (that are not affected by Summoning Scream) to link to the Hydrolyst and begin to regenerate its shields. Additionally, this will render it invulnerable to all damage until all linked Vomvalysts are destroyed. Red Glowing Vomvalysts are turned into a Blue Glowing variation which links to near Vomvalysts and has large amounts of Overshields.
*Enhanced Sentient Residue: The Hydrolyst will "bleed" teal blood on the ground after losing at least one of its Synovia, dealing a lot of damage over time to those standing on it.
*Enhanced Star Fall: Fires its gun into the sky, causing a rain of explosive, slightly homing projectiles on all targets nearby. The explosives may cause knockdown. Most of the projectiles spawn right under players. This ability can deal damage through 's Rift Plane and 's . Base area-of-effect spans a 300m radius.
*Vomvalyst Bloom Summon: Throughout the fight, the Hydrolyst summons Vomvalyst Blooms, purple portals that will periodically spawn buffed variants of the Eidolon Vomvalysts. The blooms can also link to nearby Vomvalysts, making them immune to damage, and charging them up over time. Fully charged Vomvalysts gain a large amount of overshields and are visually indicated by a bright energy aura surrounding them. The Bloom can be destroyed, but takes massively reduced damage from anything other than Operator attacks and Amps.
*Acid Rain: If at least one limb destroyed, the Hydrolyst will occasionally spawn clouds of acid rain, that cover a wide area, staining the ground green and dealing extreme damage to players standing on it.
*EMP Bubbles: The Hydrolyst will periodically create bubbles of energy, increasing in frequency as more limbs are destroyed, that float into the air and grow until they explode into Energy Spike-like waves that are much faster and do extremely high damage, potentially one-shotting any player hit. However, these bubbles are telegraphed - they are preceded by streams of gas-like particles that emit from the ground, and the bubbles themselves take several seconds to grow large enough to explode. The bubbles can be destroyed before the explosion by gunfire, Operator attacks, and Amps.
*Lightning (Passive): Throughout the fight, the Hydrolyst alters the weather around it, creating clouds of heavy rain and summoning highly damaging lightning. Small ripples of green energy on the floor briefly indicate where the lightning will strike. It seems the lightning cannot hit airborne players.
*Energy Spike: The attack Hydrolyst will use upon the destruction of one of his limbs. This will emit five pulses of highly damaging damage.
If the Hydrolyst is still alive once sunrise hits, it will change course towards the nearest body of water. Upon arriving, it will become invulnerable and disappear in a pillar of blue light as it sinks back in, and all Eidolon Lures will self-destruct. The Hydrolyst can still be killed en route as long as it has not reached the water.
==Tactics==
===General===
Dealing with the Hydrolyst is essentially the same as dealing with the Gantulyst, in that it possesses 6 Synovia (one on each knee, one on each arm, and one on each of its shoulderblades), thus requiring the use of 3 charged lures if players wish to capture it.
Much like the Gantulyst, the Hydrolyst moves quickly, forcing the Tenno to run after it at all times and making it harder to hit its weak points.
The Hydrolyst remains immune to 's abilities. For recommended Warframes to deal with the Hydrolyst, refer to the Strategy section for the Teralyst.
As powerful as they are, the majority of the Hydrolyst's attacks only affect players on the ground. Spending time airborne is an efficient alternative to the Operator's Void Mode to dodge the attacks.
===Summary===
*Preparation Phase: Damage an Eidolon Lure and hack it to take control of it. The Lure can then be charged by either letting it absorb a nearby Eidolon Vomvalyst's spectral form, or by picking up the energy orb they drop (indicated by a blue beacon) and passing it onto the Lure. Each lure needs the energy of three Vomvalysts to fully charge. It is recommended to have three lures under control by the end of the hunt.
*Phase 1: The Eidolon Hydrolyst's shield can only be damaged with damage; this can be done with the Operator's power (unlocked only after The War Within). The Synovia weak points will be vulnerable once its shields have been depleted.
*Phase 2: Take down Synovia; this will trigger an energy spike of 5 waves in a 65-meter radius and yield an Exceptional Sentient Core for each one destroyed.
**With no charged Lure: The Hydrolyst will teleport away, regenerating 75% of its shield.
**With at least 1 charged Lure: The Hydrolyst will not teleport away, regenerating only half of its shield.
*Phase 3: Once all Synovia have been destroyed, the Hydrolyst will call upon surrounding Vomvalysts to heal it. Destroy these with the Operator.
*Phase 4: The Hydrolyst's entire body will finally be vulnerable to damage. At this point it can be defeated.
**With 0-2 charged Lures (Killed): The Hydrolyst will collapse to the ground, yielding only five Eidolon Shards and an Arcane Enhancement.
**With 3 charged Lures (Capture): The Hydrolyst will be absorbed and dissolved into the ground, the Lures tethered to it explode, additionally yielding a generous amount of Sentient Cores, two Brilliant Eidolon Shards, two Radiant Eidolon Shards (one being reimbursed), two Riven Transmuters and draws from a different drop-pool of Arcane Enhancements.
***When captured, the Hydrolyst may also drop an Eidolon Hydrolyst Articula, which can be placed in the Orbiter for Decoration.
***Successfully capturing the Teralyst, Gantulyst, and Hydrolyst in a single night yields a total of 2 Riven Transmuters, 2 Radiant Eidolon Shards, 3 Brilliant Eidolon Shards, 9 Eidolon Shards, 17 Flawless Sentient Cores, 15 Exceptional Sentient Cores and a large amount of Intact Sentient Cores.
==Tips==
* can remove the Hydrolyst's armor, even while it's shielded; 25 hits will remove the Hydrolyst's armor entirely, allowing weapons to deal full damage.
*As the Hydrolyst is part of the faction, it is vulnerable to and damage, but resists .
*The increasingly chaotic nature of the Hydrolyst's attacks, coupled with the giant's increased speed, makes attacking its weak points harder than ever, while enduring increased counts of hardly-avoidable damage. Prioritize the shoulder and armpit Synovias first as they are the most difficult to target.
==Trivia==
*Eidolon in Greek literature are the apparitions of living or dead beings.
*Eidolon Synovias are a direct reference to synovial joints, which are compound joints found throughout the body.
*Hydro is Greek for water.
*The Eidolon Hydrolyst was placeholder-named as "Rainalyst" during development and is still referred to as such in the game's files.
*Eidolon Hydrolyst is sometimes referred to by the community as "Harry".
*The 3 night bosses of Plains of Eidolon together are sometimes referred to by the community as "Tridolons" (i.e. "Three Eidolons" - Eidolon Teralyst, followed by Eidolon Gantulyst, and finally by Eidolon Hydrolyst).
==Bugs==
*Even if you have charged lures to prevent the Eidolon from teleporting away, there is still a chance that it will teleport away.
*The Eidolon Hydrolyst may sometimes be killed even with 3 charged lures, randomly ignoring one. Adding additional lures can prevent this.
*When capturing the Eidolon Hydrolyst after Day begins, it may play the 'kill' animation and declare that the bounty has failed, but it will still drop shards as though it was captured.
*The Hydrolyst's Synovias display as Teralyst Synovia, rather than Hydrolyst Synovia
== Gallery ==
File:ArticulaHydrolyst.png|Hydrolyst Articula
File:HydrolystSigil.png|Hydrolyst Sigil
==Patch History==
==See also==
*Plains of Eidolon
*Eidolon Teralyst
*Eidolon Gantulyst
*Eidolon Vomvalyst
*Eidolon Shard
*Radiant Eidolon Shard
es:Eidolon Hidrolista
pt:Eidolon Hydrolyst
ru:Эйдолонский Гидролист
Category:Sentient
Category:Plains of Eidolon
Category:Update 22
Category:Enemies
Category:Grand Boss