Once-Iriis, Failed Variable

Once-Iriis, Failed Variable is powerful Scorn that was imprisoned by the Lucent Brood within Savathûn's Spire to be experimented upon.

Gameplay
Once-Iriis, Failed Variable is one of the possible final encounters of the Savathûn's Spire Activity. Upon entering the arena, Once-Iriis will be standing on top of the raised section, and start summoning reinforcements, most notably near-copies of itself called Experimental Failures. Iriis is not very mobile, strafing around and eventually teleporting to the lower platform, but can inflict high damage both with its Scorn Crossbow and its Solar burning area melee, which is also used by the Failures. In addition, Iriis will summon Ether Torches for even more area denial.

After Iriis reaches half health, the Raider will coat itself in an Immunity Shield, teleport to a pillar nearby, and summon more Failures. This will give it perfect line of sight onto a plate that the players must stand on to deactivate the shield. Once this is done, Iriis will return to the central area, and will be fully vulnerable until slain.

Appearance

 * Destiny 2: Season of the Witch