Requires

Sedris, the Traitor King must be on the battlefield. Void Maw must be on the battlefield. Altar of Dementia must be on the battlefield. Witch Engine must be on the battlefield. Mana needed:

Steps

1. Activate Altar of Dementia by sacrificing Witch Engine, causing target player to mill cards equal to Witch Engine's power.
2. Activate Witch Engine's unearth ability by paying , returning it from your graveyard to the battlefield, giving it haste and exiling it at end of turn or when it leaves the battlefield.
3. Activate Witch Engine by tapping it.
4. Holding priority, activate Altar of Dementia by sacrificing Witch Engine.
5. Both Witch Engine's undying ability and Void Maw attempt to exile Witch Engine when it would be put into your graveyard.
6. Choose to apply the Void Maw replacement effect, exiling Witch Engine.
7. Resolve the Witch Engine ability from step 3, adding .
8. Resolve the Altar of Dementia ability, causing target player to mill cards equal to Witch Engine's power.
9. Activate Void Maw by putting Witch Engine from exile into your graveyard, giving Void Maw +2/+2 until end of turn.
10. Repeat from step 2.

Results