Advanced Defense Unit

The Advanced Defense Unit (ADU) is the structure players defend in Onslaught. Waves of Fallen and Hive combatants attack it, and if it is destroyed the activity ends.

Waves and scrap

Waves come in sets of ten. Players earn Scrap by scoring and spend it on defenses at the start of each set and after the 3rd and 6th waves of a set.

Defenses

Decoys, turrets and tripmines become available once the ADU is set up, and they can be upgraded after certain waves.

Batteries

Saboteurs and Champions can drop ADU batteries. Players throw them at the ADU or at damaged defenses to repair them. Augment-wave enemies drop two batteries.

Versions

The playlist version is one set. Normal and Legend have five sets of escalating difficulty, covering 50 waves. Each boss wave opens a portal to the Pyramid Ship, and defeating the boss spawns an exit portal to the next set. Completing wave 50 spawns an extra reward chest and ends the activity.