Xavier Sal, Infested Captain + Haunted One + Thornbite Staff + Altar of Dementia

Xavier Sal, Infested Captain

Haunted One

Thornbite Staff

Altar of Dementia

How it works

1. Activate Xavier Sal's first ability by tapping it and removing a +1/+1 counter from the additional nontoken Human, Fungus and/or Pirate if it has one, or any counter from another permanent you control otherwise.
2. Xavier Sal triggers, causing it and all other creatures you control that share a creature type with it to get +2/+0 and gain undying until end of turn.
3. Resolve the Xavier Sal ability, causing you to populate.
4. Activate Altar of Dementia by sacrificing the additional Human, Fungus and/or Pirate.
5. When the creature dies, its undying ability and Xavier Sal trigger.
6. Resolve the creature's undying trigger, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
7. Resolve the Xavier Sal trigger, untapping it.
8. Resolve the Altar of Dementia ability, causing target player to mill cards equal to the sacrificed creature's power.
9. Repeat.