Mutalist Alad V

Controlled by the Infested and corrupt with power, Mutalist Alad V is the boss of Eris introduced in Update 15.5. To fight him, players need to craft the Mutalist Alad V Assassinate Key with the blueprint awarded from completing the Patient Zero quest.

Completing the assassination mission will award a component - Helmet, Systems or Chassis - necessary to build the Mesa Warframe.

Appearance
Like the Mutalist Osprey, half of Alad is still his original self, but Infested mass has spread all over his other arm, leg, and body. No longer accompanied by his Zanuka, Alad V is forced to fend for himself with a Paracyst rifle.

Paracyst Rifle
Alad V often fires in short bursts that deal high damage, bypassing shields. It is capable of applying a proc, which will often deal high and fatal DoT to Tenno with low health not equipped with Antitoxin, and can also apply a  proc.

Nanite Aura
Alad V is shrouded in a swarm of nanites, slightly damaging nearby Tenno if they are too close.

Infested Barrier
Alad V removes his collar and deploys it on the ground as a temporary cover to hide and shoot behind. Weapons with punch through can penetrate the barrier and damage Alad. Once he has taken enough damage, he will reequip his collar.

Biomass Launcher
While the Infested Barrier is active, it will periodically shoot out multiple projectiles that can deal and proc damage.

Flare Burst
If any Tenno wander too close to Alad V when he deploys the Infested Barrier or when the Barrier is active, the Barrier will explode in a burst of flame, knocking back anyone who is too close.

Collar Beam
Alad V removes his collar and releases a continuous electrical beam that deals very high damage at a rapid rate. If his target is out of range or behind cover or Alad has taken enough damage, he will stop the attack and reequip his collar.

Collar Throw/Mind Control
Alad V removes his collar and throws it similarly to a Glaive at the closest Tenno. However, the collar does not bounce across surfaces, and can track and follow fleeing Tenno. If the collar connects to a Tenno, it will be forced under Alad V's will, and will automatically attack allies. The controlled Tenno is marked by an orange link to Alad, and can be rescued by damaging Alad enough. If fighting Alad V alone, the collar will explode on impact, staggering the Tenno and depleting their shields.

Strategy
Alad V is completely invulnerable to all types of damage while his collar is equipped. Alad V becomes vulnerable when he attempts to attack back with his collar. When another Tenno is controlled, the others should concentrate fire on Alad V while avoiding attacks from the mind-controlled Tenno. and attacks can still proc even when Alad is invulnerable, though the damage is only dealt when his collar is removed.

Throughout the battle, various Infested units will spawn in, increasing the danger level of the mission when Tar-Mutalist MOA attempt to slow the Tenno down and Swarm-Mutalist MOA apply nanite swarms across the area. A powerful melee weapon with Life Strike can help replenish the damage dealt by Alad V.

Bugs

 * After Alad V's mind control, players may fall through the map upon recovery.
 * Occasionally after spawning, he may stand still and become non-hostile, refusing to remove his collar, thus making him invincible until the mission is restarted.
 * When Alad V Spawns there is a chance your screen wil go very dark, however falling out of the map seems to fix it.

Trivia

 * Alad V is the first boss to become Infested.
 * Despite his radically altered form, he still possess the same mod drops as his original self.