Supermassive (10 player)

Damage Algalon the Observer and focus on killing Collapsing Stars in close proximity to one another. Black Holes are formed when Collapsing Stars die, so position their deaths as close together as possible — ideally two right next to each other and a third relatively nearby.

Once Black Holes are formed, kite the Living Constellations directly into them. Stand next to two adjacent Black Holes and wait for Living Constellations to approach, then lead two of them into those holes before sprinting to close the third. The achievement triggers the moment the third Black Hole is closed, not when the boss dies.

Never step on a Black Hole yourself, as doing so will instantly remove you from the encounter. Also avoid reaching 5 stacks of Phase Punch, as that will phase you out and reset the boss. Note that closing the holes and defeating Algalon save as separate events, so you do not need to kill him on the same attempt.