Hydroid

• Hydroid marks a targeted location for orbital bombardment over unrestricted range, calling forth an artillery barrage-like salvo of water missiles from above to strike the marked area 3 / 5 / 8 / 10 meters in radius for 2 / 3 / 4 / 5 seconds. Water missiles launch from above in a salvo of 4 per second, with each missile exploding on impact dealing 50 / 75 / 100 / 150 Impact damage and Knockdown enemies within a 5 meters explosion radius.
  • Damage per missile is affected by Ability Strength, while number of missiles per salvo is not.
  • Damage does not bypass obstacles in the environment and does not diminish with distance.
  • Duration is affected by Ability Duration.
  • Explosion radius is affected by Ability Range, while area radius is not.
  • Casting speed and charging speed are affected by  Natural Talent and  Speed Drift.
  • The barrage distinctly resembles a salvo of cannon-fire from an old warship. Like said salvo, it is not terribly accurate, but can threaten a wide area for several seconds and an enemy can be struck multiple times.
  • Water missiles have a high chance to strike both grounded and airborne targets directly.
• Tapping the button (default 1 ) initiates the ability cast immediately. Holding the button for up to 2.5 seconds allows Hydroid to charge Tempest Barrage for up to 200% damage per explosion and increased barrage duration, in exchange for double energy cost.
  • Holding highlights the area around the aiming reticle in Hydroid's energy color, allowing free aim before releasing the hotkey to cast Tempest Barrage at the target location.
    • While charging, an audible flowing liquid sound plays.
  • The barrage will be centered on the spot where the reticle is pointing up to the first solid object within view. This allows Tempest Barrage to be cast at distant locations as long as one has line of sight. Note that it tends to fall short if cast through a door or gateway.
  • The barrage spot is decided upon releasing the cast; you can move the reticle freely before releasing the ability button.
  • When cast on Snow Globe it will not be able to strike through it, but when cast within it will fall through it normally.
• Can be cast during Undertow over unrestricted range. Submerged enemies receive damage from Tempest Barrage.
• Tempest Barrage is a One-Handed Action that allows casting during movement, while midair, and on ziplines.
• Can be recast while active to create multiple barrage instances.
• Water missiles and their impact indicator circles are affected by Hydroid's chosen Warframe energy color.
• Breaks containers and damages turrets/cameras.

Main article: Corroding Barrage

Corroding Barrage is a Warframe Augment Mod for Hydroid where each projectile of Tempest Barrage has a percent chance of inflicting a Corrosive status effect.

Rank	Corrosive Status Chance	Cost
0	50%	6
1	65%	7
2	80%	8
3	100%	9

• Tap 1  to quickly cast a short-lived barrage at the location you aim. Holding the hotkey will increase damage, duration and cost by up to 100%.
• Mod for Ability Range to increase the explosion radius of each water missile, allowing more enemies to be damaged and knocked down inside and around the barrage area.
• Cast multiple barrages in different directions to lock down chokepoints from incoming enemies.
• Combo with Undertow and Tentacle Swarm to inflict continuous damage and keep enemies from escaping.

• Hydroid transforms into liquid and surges forward as a wave of water. While traveling in waveform, Hydroid becomes completely invulnerable to damage, as his speed increases to 20 / 25 / 27.5 / 30 meters per second over a duration of 1 second. Enemies within 3 / 4 / 5 / 6 meters of the wave are ragdolled and pulled along by the riptide, while dealt 100 / 200 / 250 / 300 Impact damage as the wave travels and 100 / 200 / 250 / 300 Slash damage as the wave breaks at the end of the duration.
  • All damage is affected by Ability Strength. The Slash damage component diminishes with distance and is affected by body-part multipliers.
  • Wave speed is affected by Ability Duration, while travel duration is not.
  • Striking radius is affected by Ability Range.
• While traveling in waveform, activating Undertow halts Hydroid at his current position and transitions directly into liquid form on impact with the ground.
  • Enemies pulled by Tidal Surge will sink into Undertow as it forms.
  • Likewise, deactivating Undertow while traveling in waveform halts Hydroid at his current position, causing him to emerge from the pool.
• Can be cast while in Undertow liquid form to travel half the normal distance.
  • Enemies previously drowning within Undertow will be pulled along by Tidal Surge.
  • Hydroid remains in liquid form during and after Tidal Surge as long as Undertow remains active.

Main article: Tidal Impunity

Tidal Impunity is a Hydroid Warframe Augment Mod for Tidal Surge that allows Hydroid and all allies contacted by the ability to temporarily gain immunity to Status Effects, as well as removing already active ones.

• It can be used to reach or pass certain areas of the map.

• Hydroid submerges into a pool of water with a 1.5 / 2.5 / 3 / 4 meters radius, becoming invulnerable to damage and untargetable by enemies. Enemies that wander onto the pool sink and disappear from sight, become suspended in a Knockdown state, and drown taking 10 / 15 / 20 / 25 base Impact damage per second; drowning enemies also receive 1% / 1.5% / 1.7% / 2% of their maximum health as Impact damage, which continuously stack every second while enemies remain submerged.
  • Base damage and damage increase per second are affected by Ability Strength.
  • Radius is affected by Ability Range.
    • Undertow uses the following expression when accounting for Ability Range: Modified Range = Base Range × Ability Range ^0.5
  • Casting speed is affected by  Natural Talent and  Speed Drift.
  • Damage increase per second applies to each individual enemy. The stacked damage for a single enemy resets to base damage when the submerged enemy exits the pool.
  • Submerged enemies receive increased damage proportionate to the number of enemies inside Undertow.
  • The current number of submerged enemies trapped within Undertow is displayed on the ability icon.
  • Allied players can shoot into Undertow to contribute 50% of their total damage from weapons and abilities, distributed evenly to all submerged enemies.
  • Status Effects apply to all submerged enemies, with their effects and debuff timers paused until enemies exit Undertow.

• While active, Hydroid can aim at an enemy target within 10 / 12 / 13 / 15 meters and press the primary attack key (default LMB ) to expend 5 energy, launching a water tendril from the pool, grabbing the target and pulling it into Undertow.
  • Grab range is affected by Ability Range.
  • Energy cost per grab is affected by Ability Efficiency.
  • If the targeted enemy is unable to be pulled, the tendril will release it after a few seconds.
  • Released bodies may make enemies suspicious and stop short of the pool. This will often result in them walking away from the puddle, requiring Hydroid to pull them in manually.

• Undertow drains 6 / 4 / 3 / 2 energy per second, and will remain active so long as Hydroid has energy. Undertow will end if Hydroid runs out of energy, jumps (Space ), rolls (2x Shift ), or if deactivated by pressing the ability key again (default 3 ). Hydroid can slowly move while in Undertow by draining 1 energy point per 0.2 meters moved.
  • Activation and travel energy costs are affected by Ability Efficiency, and the channeling energy cost is affected by both Ability Efficiency and Ability Duration.
  •  Energy Siphon and other energy restoring effects are deactivated while Undertow is channeled. However, Arcane Energize, Orokin Void Death Orb energy restores, Syndicate effects such as Blight and Entropy can still restore energy.
  • If moving while in undertow you can sprint (hold Shift ) for faster movement speed. Mods that affect sprint speed also work with this.

• While hidden in his liquid form, Hydroid can cast all other abilities which exhibit similar and altered effects:
  • Tempest Barrage can damage submerged enemies within Undertow.  Corroding Barrage can also proc Corrosive on submerged enemies.
  • Tidal Surge allows Hydroid to remain submerged in Undertow and travel in waveform for half the normal distance.
    • Undertow will not drain additional energy when Hydroid moves via Tidal Surge.
    • Enemies previously submerged in Undertow will be pulled along by Tidal Surge.
  • Tentacle Swarm centers the kraken on Undertow and spawns tentacles inside the pool. Charged cast can extend tentacle spawn radius outside Undertow.
    • Tentacles will capture enemies when they emerge from Undertow.
    • Tentacle Swarm deals 200% damage when cast from Undertow.

• Hydroid's Companion will also be submerged, regardless of distance from him. His companion will not become invulnerable and is susceptible to damage from explosions.
• Enemy corpses will be released from Undertow when killed.
• Cannot switch, fire, or reload weapons, perform parkour Maneuvers except jump and roll, nor collect Pickups while in liquid form.
• Can be cast while in midair to enter liquid form. Undertow pool will form when Hydroid lands on the ground.

• Aura effects from enemy Eximus will not apply to Hydroid while he is submerged but nearby Tenno will suffer from the effects of the Eximus unit's aura if they are in range.
  • Energy Leech Eximus still will drain energy when in the pool, however.

• When Hydroid is submerged, the game treats him as invisible to enemies. As such, any kills on unalerted enemies with undertow will count as a stealth kill.
  • Also causes the Zenistar to deal bonus stealth damage to enemies.
    • There is a bug related to this where a Zenistar built with blast will continue to deal bonus damage to some enemies even when Hydroid re-emerges from the puddle.

• Submerged enemies cannot prevent Tenno from capturing an Interception point. This makes it incredibly efficient at completely locking down towers on Interception missions.

Main article: Curative Undertow

Curative Undertow is a Hydroid Warframe Augment Mod that allows Undertow to heal Hydroid and his allies within range by a percentage of their max health every 1.5 seconds, draining additional energy for each ally in the pool.

• Undertow will knockdown enemies within range when they sink into the puddle. Activating then deactivating Undertow allows you to set up Ground Finisher attacks with your melee weapon on nearby enemies.
• If you see an enemy Eximus walk into the pool, deactivate Undertow and expose them to attacks, as their Auras will remain active while submerged.
  • As Energy Leech Eximus are still able to steal energy from Hydroid while in the pool, it's ill advised to drag them in. It's safer to cast Tempest Barrage or Tentacle Swarm on their location when they are far away to avoid losing massive amounts of energy per second.
• When running an Infested Defense (such as an uncontested Dark Sector or Orokin Derelict), stand near the cryopod or a walkway to the cryopod and activate Undertow. Once you've collected several enemies, deactivate Undertow and chain together Area of Effect skills such as Tempest Barrage and Tentacle Swarm.
• If you are under heavy fire, activate Undertow to regenerate your shields, as well as health depending on whether your squad has a member with the  Rejuvenation aura equipped.
• Undertow is useful for gathering large numbers of enemies in one spot for another player to kill them once the ability has ended.
• Undertow cannot be used to bypass corpus laser doors by itself.

• Some bosses, such as General Sargas Ruk can be submerged by Undertow, making them invulnerable to outside damage by other players.
• Enemies see dead bodies that are killed and will often refuse to enter the pool. This requires the use of hydroid to manually pull them in.
• A sentinel equipped with  Vacuum will still attempt to suck up loot while in the pool, which blocks the player's reticle and prevents them from targeting enemies to drag into the pool.
  • This will slightly alleviate itself after staying in the pool for an extended period, as sentinels will "freeze up" and stop moving if the player idles for too long.
• Cameras can be targeted, but cannot be tentacled in.
• Downed Bursa will stay in undertow and count as alive there.

• Hydroid summons a creature from the deep, causing 4 / 6 / 8 / 10 tentacles to emerge from all surfaces within a marked location 3 / 3 / 5 / 5 meters in radius, cast over unrestricted range. Tentacles prioritize spawning beneath enemies inside the radius, with each tentacle capturing their initial targets or throwing them upward, dealing a maximum of 75 / 150 / 225 / 300 Magnetic damage upon emerging, on first contact with enemies, and when submerging as the ability expires after 10 / 13 / 18 / 20 seconds. Captured enemies are incapacitated in a ragdoll state and stay attached to the flailing tentacles; bypassing Shields 50 / 100 / 150 / 200 True Damage will be dealt per second.
  • Tentacle Magnetic damage and True damage per second are affected by Ability Strength, while number of active tentacles is not.
    • Magnetic damage calculation when accounting for Ability Strength is squared (e.g., with a maxed  Intensify, the tentacles will deal a maximum of 300 × 1.3^2 = 507 Magnetic damage at rank 3).
  • Magnetic damage is effective against Shielded and Proto Shields, but less effective against Alloy Armor.
  • Magnetic status effect reduces a target's current and maximum shields by 75% for 4 seconds.
  • Spawn radius is affected by Ability Range.
  • Duration is affected by Ability Duration.
  • Casting speed and charging speed are affected by  Natural Talent and  Speed Drift.
  • Tentacles detect and capture new enemy targets when they come into range.
  • Tentacles can capture multiple enemies at once.
  • Tentacles with captured enemies will flail their victims around slowly, allowing players to take aim and kill their targets.

• Tapping the button (default 4 ) casts the ability immediately. Holding the button for up to 2.5 seconds charges Tentacle Swarm, increasing the number of tentacles spawned up to 8 / 12 / 16 / 20 and spawn radius up to 300%, in exchange for up to double energy cost.
  • Tentacle Swarm's spawn area will be highlighted by Hydroid's energy color during the casting and charging animations.
  • Spawn area indicator visibly grows in size as Tentacle Swarm is charged.
  • While charging, an audible whale-like call from the Kraken plays.

• Can be cast while in Undertow liquid form to center Tentacle Swarm on the pool.
  • Quick cast causes all tentacles to spawn inside Undertow's radius, while charged cast extends the spawn radius outside of Undertow.
  • Tentacle Magnetic damage and True damage per second deal 200% damage when cast from Undertow, including tentacles that spawn outside Undertow.

• Casting Tentacle Swarm is a two-handed action that stops Hydroid's movement and other actions. Charging Tentacle Swarm is a two-handed upper body animation that allows player movement.
• Can be recast while active; however, only one instance of Tentacle Swarm can be active at a time. Recasting will replace the previous instance.
• Hydroid briefly summons the Kraken at the center of the spawn area as a visual effect. The Kraken emerges from a pool of water, then submerges slowly and disappears. Kraken is affected by Hydroid's chosen Warframe appearance and energy colors.
• Tentacles appear as translucent water tendrils emerging from a small puddle of water. Tentacles emit splashes of water periodically, as well as a steam particle effect at their base which is affected by Hydroid's chosen Warframe energy color.

Main article: Pilfering Swarm

Pilfering Swarm is a Hydroid Warframe Augment Mod that grants Tentacle Swarm a chance to yield additional loot from enemies killed while they're ensnared by the tentacles.

• Does not trigger Arcane Trickery enhancement.