Eidolon Teralyst

Teralysts are gigantic Sentient creatures found on the Plains of Eidolon at night. They are remnants of a Sentient that was defeated in a battle against the Tenno during the Old War, and now wander the plains perpetually searching for their lost components. Despite this, they are still formidable creatures  armed with powerful attacks and durable defenses, and are hostile to both Tenno and Grineer alike.

Behavior
Teralysts generally walk in one direction, even if Tenno are nearby, though their attention can be drawn to specific locations by using Eidolon Lures found throughout the Plains at night.

Once one of the Teralyst's Synovia weak points has been destroyed, it will emit 5 massive (60 meter radius) energy waves that proc after a short delay, and then teleport to a random part of the map unless it is chained by a fully charged Eidolon Lure.

The Teralyst has many attacks, though all of them have noticeable telegraphing:


 * Ground Stomp: Stomps the ground, sending out a shockwave that pushes back any Warframe or Operator in its path a great distance. Jumping will dodge this shockwave.
 * Ground Smash: Sends a series of explosions to each Tenno's current position. Moving after the ability is cast can successfully prevent damage.
 * Gun Swing: The Teralyst swings its gun (left) arm in a wide arc. The gun may be firing during this action, creating a 2 meter wide beam.
 * Star Fall: The Teralyst fires its gun into the air, causing a massive amount of explosive projectiles to rain down on all targets nearby. Being in the air seems to avoid the damage outright. This ability can deal damage through Limbo's Rift Plane and Frost's Snow Globe.
 * Seeking Bullets: A sphere of light is emitted from the Teralyst's back. After a short delay, it will split into multiple projectiles that will seek out any nearby targets. These however are not very accurate, and are easily dodged.
 * Tree Swing: Swings its right arm in a short arc, dealing damage in an area.
 * Sentient Residue: The Teralyst will "bleed" damaging residue on the ground randomly after losing at least one of its Synovia. This deals damage over time to players standing on it.
 * Summoning Scream: The Teralyst glows orange and screeches into the air. This will summon and buff Vomvalysts around it.
 * Regenerating Scream: The Teraylst glows blue and screeches. This will cause surrounding Vomvalysts (that are not affected by Summoning Scream) to link to the Teralyst and begin to regenerate its shield. Additionally, this will make it invulnerable to all damage until all linked Vomvalysts are destroyed.
 * Additionally, destroyed arm Synovias will emit Seeking Bullets, and leg Synovias will shoot out arcing shots of Sentient Residue.

Strategy
The Teralyst has many different attacks and several do extremely high damage, but they are all telegraphed. Once acquainted, players should be able to easily avoid the most damaging attacks.

Recommended equipment
Weapons with a high damage to ammo ratio. Snipers and shotguns are ideal for this purpose. Explosives are ineffective on the weak point phases as they will 'hit' the body and deal no damage.

Due to possessing both Alloy Armor and Robotic health, weapons equipped with damage will do maximum damage (+75% vs Alloy Armor, +25% vs Robotic), whilst  will also be reasonably effective (+25% vs Alloy Armor, +15% vs Robotic). Avoid and  as much as possible. is recommended to decrease Teralyst`s armor but has no effect on its shields.

The Teralyst is immune to all non-damage effects of warframe powers, as well as all status effects. Therefore, highly defensive and/or self/squad buffing warframes such as Rhino's Iron Skin & Roar, Trinity's Blessing, Chroma's Cold Elemental Ward and Vex Armor, Volt's Electric Shield, or Harrow's Covenant are good choices.

Titania's Razorwing enables her to fly above virtually all of the Teralyst's attacks and allows her to deal immense amounts of damage. Stay moving to avoid fire from the Vomvalysts.

Limbo's Rift Plane can dodge all but the charges of the Vomvalysts, the Star Fall attack, and the explosions upon the destruction of a weak point.

Chroma can one-hit kill the Teralyst's weakpoints and the creature itself using Vex Armor's Fury buff and high damaging weapons such as Opticor. Fury is best charged by unequipping the sentinel's mod or equipping a Decaying Dragon Key to reduce overall shields and prevent Scorn from increasing too much armor, and then using self-damaging weapons such as Angstrum or Hikou modded with. Alternatively, players can use Toxin to damage their health while bypassing shields. Recommended weapons for this strategy are thrown melee weapons like Cerata, using and Toxin damage mods.

Harrow's Covenant can be used to render the squad immune to the proc of the energy wave the Teralyst emits. Duration should be normalized, as to not interfere with Chroma's Vex Armor.

Nyx's Absorb ability and augment can be used to avoid any kind of damage and a 'calm' hand for hitting the sensitive spots. Furthermore its easy to revive fallen Tenno.

During any phase of the battles, players can bring Eidolon Lures into the battle and charge them by letting them absorb three Vomvalysts energies either by letting the lure absorb their ethereal form or by looting their energy pickup (as marked with a teal light pillar) and bringing it to the lures. Once the lures are charged, the lures will glow blue and if brought near the Teralyst before a part is destroyed will prevent the Teralyst from teleporting away.

Stage 1
First the shields have to be removed, as until this is done the Teralyst cannot be damaged. Using the Operator's Void Beam is the only way to remove the shields. Dashing in and out of Transference or using Void Mode can help prevent damage during this stage, allowing all members to focus on removing the shield instead of healing others.

While the Teralyst's shields are down, four weakpoints called Teralyst Synovia, located on knee and elbow joints, become vulnerable to damage from regular weapons. It is advisable to reduce the health of all Synovia to around 15 percent before destroying one as the Teralyst cannot use its Regenerating Scream until at least one of the Synovia have been destroyed. This approach effectively eliminates the chances of Regenerating Scream taking place, and dramatically accelerates the encounter.

Once a weak point is destroyed, the Teralyst will drop a Exceptional Sentient Core, drop to the ground and become invulnerable, and emit 5 damaging pulses dealing 1000 damage per pulse in a 60m radius with a guaranteed  proc. The blast comes after a delay and takes time to expand, allowing players to get out of the radius or enter the Operator's Void Mode to escape it.

If a fully charged hacked Eidolon Lure is present near enough to the Teralyst, any present lure will chain itself to one of the Teralyst's broken limbs. Each lure can chain itself up to maximum of two broken limbs. If there is a lure chained to the Teralyst, the players can continue the fight uninterrupted after a limb is broken. The Eidolon Lures do not take damage from the Teralyst's energy spike, so players should focus on surviving the blast.

Once the Teralyst recovers, it will regenerate a portion of its shields, and the process must be repeated until all its weakpoints are destroyed. If there are no charged lures, the Teralyst will teleport away (recovering full shield), and the players will have to search for it again to resume the fight.

Stage 2
Once two weak points have been destroyed and the Teralyst is at 50% health it will begin two new attack patterns and modify one of the previous.


 * Firstly, the Teralyst will charge its arm cannon and fire a projectile directly into the sky. Shortly thereafter, a hailstorm of homing projectiles will fall from the sky, saturating a large area around the Teralyst. These detonate upon colliding with the ground, but also have some homing capabilities, so staying airborne might help avoid nearby explosions, but not direct hits.
 * Secondly, the Eidolon Vomvalysts spawned around the Teralyst will launch exploding spheres similar to but weaker than the Teralyst's seeking bullets. The best countermeasure is simply keeping the number of Vomvalysts to a minimum. Keeping the number of Vomvalysts under control is both critical in helping to mitigate damage done to operators and lures, as well as reduce the Teralyst's shield recovery should it let forth a regenerating scream. During the regenerating scream, nearby Vomvalysts will latch on to the Teralyst, rendering it completely immune to damage and regenerating its shields until each linked Vomvalyst is destroyed.
 * Finally, the AoE fissure stomp where teal blasts pop up will begin to occasionally spread in a starburst pattern rather than merely circling from the front to the back. This pattern does not change until all weak points have been destroyed.

Stage 3
Once three Synovia have been destroyed, the Teralyst will attack more frequently, and Ground Stomp will be followed by a slower blue ring that will release a multitude of seeking projectiles from the ground. The Vomvalyst spawn rate will increase notably, and it is recommended to kill them quickly before they overwhelm the players.

Stage 4
After the final weak point is destroyed, the Teralyst will drop down and become invulnerable. At this point it will have roughly 20% health remaining. While downed, groups of Eidolon Vomvalysts in their ethereal form will slowly gather to the Teralyst, healing it. The player should intercept and kill as many as possible. This will continue for several seconds. After this phase, the Teralyst does not regain its shields, though it may still cast Regenerating Scream. The Teralyst can be killed entirely once it has risen from the ground, and players should do so quickly so as to prevent it from prolonging the fight. Its attack patterns in stage 4 closely resemble those exhibited during stage 3.

Once the Teralyst dies, it will collapse to the floor before slowly sinking into the ground, dropping an Eidolon Shard as well as one of the, , , or mods.

If the Teralyst is chained by two hacked and fully charged Eidolon Lures upon death, it will instead be lifted into the air and vaporized by the lures. To know that the Teralyst can be captured in this way, listen for the Quills' comment "Sentient energy contained, you are closing on victory. Act now!" If successfully killed while chained, the Eidolon Lures tethered to it will explode and yield an additional four Intact Sentient Cores, two Exceptional Sentient Cores, a Flawless Sentient Core, and a Brilliant Eidolon Shard, all of which drop from the lures, and not the corpse of the Teralyst.

Tips

 * The Operator's Void Mode is the best way to avoid damage from all of the Teralyst's area of effect attacks, as Void Mode renders the Operator immune to all forms of damage, while leaving the Warframe similarly invulnerable to attack while the Operator is out. Companions remain vulnerable however, so using Void Dash to escape attacks and exiting Transference to teleport your warframe as well as your vulnerable companions away might be a better solution.
 * Alternatively, Harrow's Covenant grants temporary invulnerability to damage and status effects to all allies within affinity range, making the entire squad immune to damage for a short duration. This is most useful after destroying the Teralyst's Synovias, as Covenant can protect the squad and their Companions from the effects of the Teralyst's energy-draining attacks, removing the need to escape from the attack's range. As a side effect, with enough duration Covenant can increase the critical chance of the squad's weapons using the Teralyst's own attack in time to deal damage to the Teralyst's weakpoints afterwards.
 * The Shwaak Prism greatly aids against the Eidolon Sentients, with its innate Punch Through dealing multiple counts of damage to the Teralyst as well as killing groups of Eidolon Vomvalysts.
 * It is recommended that players with Eidolon Lures following them should not be the main source of damage in the squad, as the lures seem to frequently drift in front of the player, blocking shots and preventing the player from damaging the Teralyst.
 * Throughout the fight, only one fully charged Eidolon Lure is required until all four Synovia are destroyed. At this stage, you can opt to bring in all Lures collected to absorb the Vomvalysts to deny the Teralyst's healing. This way, if there is a member "babysitting" the Lures there will be more time to focus on finding Lures for the final invulnerability phase.
 * If the Teralyst does teleport away, it will emit a highly visible pillar of light wherever it arrives. Additionally, all nearby Vomvalysts will attempt to reconvene with the Teralyst, regardless of distance. A Titania in Razorwing or any player with an Archwing Launcher can easily fly up and locate the pillar.
 * Similarly, upon entering the fields, the Teralyst's initial spawn will be accompanied by the same pillar of light, which is clearly visible from the air.
 * Trinity's Blessing is invaluable for healing Eidolon Lures, especially against the Teralyst's area-of-effect attacks. Her abilities are also useful in keeping Companions alive against said attacks.
 * An Energy Vampire Trinity is not advised as Eidolon Vomvalysts in their spectral form are unaffected by Energy Vampire, which may be a problem for groups that kill Vomvalysts as fast as possible.
 * While less effective at doing so, Oberon's Renewal ability can provide a similar level of healing to better sustain Teralyst attacks. Additionally, Oberon can use his Hallowed Ground plus Renewal combo to cast the Iron Renewal armor buff on allies, making them more resistant to attacks.
 * Hallowed Ground skill will nullify the Proc effect from the pulse burst, but not the damage.
 * Amesha's abilities are very useful for the fight:
 * Benevolent Decoy can absorb the Star Fall and Seeking Bullets attack and turn them into healing pulses.
 * Warding Grace can block the Teralyst's magnetic procs.
 * Vengeful Rush can be used to render you and your allies invulnerable while they don't have a full energy pool.
 * This can be used to tank the Teralyst's magnetic blasts between stages.
 * Itzal's Cosmic Crush can be used to vacuum all the Teralyst loot in one place.
 * If the Teralyst is still alive shortly before sunrise, 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, preventing any further progress and forcing players to wait until the next night to fight a new one. The Teralyst can still be killed en route as long as it has not reached the water, provided there is no more than a single Synovia remaining. When Onkko warns the player of the impending sunrise, all lures will inevitably self-destruct, and capture will become impossible.
 * Konzu's bounty reset timer coincides with when the Teralyst will flee.
 * can remove the Teralyst's armor, even while it's shielded; 50 hits will remove the Teralyst's armor entirely, though doing so will also remove its weakness to damage. Hitting the Teralyst 49 times instead will minimize its armor and retain its damage weakness.
 * Unlike all other bosses, Nova's Molecular Prime has no effect on the Teralyst.

Bugs

 * After killing a Teralyst, the doors back to Cetus may not open.
 * Exceptional Cores may not drop for some players or be dropped up to 30m away.
 * The Teralyst may occasionally begin rapidly flying upwards, then abruptly fall to the ground shortly after reaching the height limit.
 * The Teralyst may randomly turn invisible during the fight. It is still possible to damage the shield/limbs with certain weapons, however the hit-box for the limbs is inconsistent and may require many 'test shots' in order to damage one successfully. If a limb is destroyed while it is in this state it will instantly teleport to a random spawn location.
 * Due to a 0.02% drop rate that is un-accounted for, the Teralyst may drop one of the slash set mods (,, or .) This is likely unintended as you must abort the mission and loose all rewards to leave. (Unconfirmed.)

Trivia

 * It was revealed on Devstream #102 that Eidolon vocal sound effects were made using humpback whales' calls.