Mikaeus, the Unhallowed + Cauldron of Souls + Intruder Alarm + Animate Artifact + Ashnod's Altar

Mikaeus, the Unhallowed

Cauldron of Souls

Intruder Alarm

Animate Artifact

Ashnod's Altar

How it works

1. Activate Ashnod's Altar by sacrificing the additional nontoken non-Human creature, adding CC.
2. When the creature dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
3. When the creature enters the battlefield, Intruder Alarm triggers, untapping all creatures.
4. Activate Cauldron of Souls by tapping it, giving the creature persist until end of turn.
5. Activate Ashnod's Altar by sacrificing the creature, adding CC.
6. When the creature dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
7. When the creature enters the battlefield, Intruder Alarm triggers, untapping all creatures.
8. Repeat.

This clever loop relies on turning Cauldron of Souls into an active creature using Animate Artifact, allowing it to untap alongside your board every time Intruder Alarm triggers. Once animated, you can tap it to grant persist to a non-Human creature that already has a +1/+1 counter from Mikaeus, the Unhallowed's undying anthem. When you sacrifice that creature to Ashnod's Altar for mana, its +1/+1 and -1/-1 counters annihilate each other upon death, letting its persist and undying abilities alternate indefinitely to fuel infinite colorless mana and untap your entire team.