Xavier Sal, Infested Captain + Haunted One + Intruder Alarm + Umbral Collar Zealot

Xavier Sal, Infested Captain

Haunted One

Intruder Alarm

Umbral Collar Zealot

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 Umbral Collar Zealot by sacrificing the additional Human, Fungus and/or Pirate.
5. When the creature dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
6. When the creature enters the battlefield, Intruder Alarm triggers, untapping all creatures.
7. Resolve the Umbral Collar Zealot ability, putting a +1/+1 counter on it.
8. Repeat.

This clever loop is orchestrated by Xavier Sal, Infested Captain, whose tap-abilities fuel a continuous cycle of sacrifice and rebirth. By sacrificing a creature to Umbral Collar Zealot, you trigger Haunted One's passive bonus, granting that dying creature undying so it immediately returns with a +1/+1 counter. That new entry instantly wakes up the entire board thanks to Intruder Alarm, untapping Xavier Sal and your other creatures so you can strip away the +1/+1 counter to populate, or feed the zealot once more.