Tentacle Swarm

ENERGY: 50-100 KEY 4	Tentacle Swarm Tap to spawn watery tentacles from all nearby surfaces to wreak havoc. Charge to increase the number of tentacles and spawn area. Use while in Undertow to have the tentacles emerge from the pool.	Strength:75 / 150 / 225 / 300 ( Magnetic contact damage) 50 / 100 / 150 / 200 ( True capture damage per second)
		Duration:10 / 13 / 18 / 20 s
		Range:3 / 3 / 5 / 5 m (base radius) 9 / 9 / 15 / 15 m (charged radius)
		Misc:∞ (cast range) 4 / 6 / 8 / 10 (tentacles) 8 / 12 / 16 / 20 (charged tentacles) 200% (damage bonus from Undertow)

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 $300 \times 1.3^2 = 507$ Magnetic damage at rank 3).
- Magnetic damage is effective against Shielded and Proto Shields, but less effective against Alloy Armor.
- Magnetic status effect amplifies damage to the shields of the afflicted target by 100% and nullifies natural shield regeneration for 6 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.

Ability Synergy: 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. However, when the ability is cast by Hydroid/Prime, the tentacles will be opaque and more organic in appearance.

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.