Mikaeus, the Unhallowed + Umbral Collar Zealot + River Kelpie

Mikaeus, the Unhallowed

Umbral Collar Zealot

River Kelpie

How it works

1. Activate Umbral Collar Zealot by sacrificing River Kelpie.
2. When River Kelpie dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
3. When River Kelpie enters, its first ability triggers, causing you to draw a card.
4. Resolve the Umbral Collar Zealot ability.
5. Activate Umbral Collar Zealot by sacrificing River Kelpie.
6. When River Kelpie dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
7. When River Kelpie enters, its first ability triggers, causing you to draw a card.
8. Resolve the Umbral Collar Zealot ability.
9. Repeat.

This clever loop centers on the dynamic interplay between River Kelpie's persist ability and the undying granted by Mikaeus, the Unhallowed, which alternatively place -1/-1 and +1/+1 counters on the Kelpie to systematically cancel each other out upon death. Umbral Collar Zealot acts as the sacrificial engine that repeatedly sends the Kelpie to the graveyard, while also letting you filter your draws with its surveil ability. Because River Kelpie's own trigger rewards you with card draw every time it enters the battlefield from the graveyard, sacrificing and recurring the Kelpie over and over lets you rip through your entire deck at will.