The two pillar phases

Two arenas, one useful obstacle[1]
  1. First arena

    Bait the lunge

    Weapons cannot hurt it yet. Shelter behind a pillar from shockwaves; bait its lunge into the pillar when it screams and rears back.

  2. Second arena

    Follow and finish

    After it retreats, follow it. Weapons now hurt it; continue dropping pillars for damage.

Threats to watch[1]
ThreatResponse
Ground smashUse pillars as cover.
TickerUse the melee/kick input; the guide’s Xbox layout uses B.
JuviesWatch for reinforcements during the fight.

Which achievement unlocks?

Defeating this Corpser triggers Get Back You Eight-legged Freak.[1][2]

Corpser Invasion Events

Horde Siege has its own Corpser Invasion Event. The official reveal describes a map-wide alert, supporting enemies, shared rewards and temporary modifiers affecting every squad.[3]

The September 30 multiplayer update fixed blast charges failing to register when delivered during the Corpser Invasion Event. It also made all Invasions harder and reduced participation rewards. Follow the event’s blast-charge objectives when playing Horde.[4]

Continue the Act 3 route, or prepare for multiplayer with the Horde Siege guide.

Sources & further reading

  1. Firsthand Corpser encounter: Act 3, Chapter 2 pillar phases, screenshots and videoGamer Social Club · Adam “Addy” Stewart · October 1, 2026
  2. E-Day official achievements list (campaign hints)Xbox Wire · September 9, 2026
  3. E-Day Multiplayer Deep DiveThe Coalition · July 30, 2026
  4. Emergence Begins — Tomorrow: launch weapon tuning and enemy fixesThe Coalition · September 30, 2026