Mikaeus, the Unhallowed + Thermopod + River Kelpie

Mikaeus, the Unhallowed

Thermopod

River Kelpie

How it works

1. Activate Thermopod 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. Activate Thermopod by sacrificing River Kelpie.
5. When River Kelpie dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
6. When River Kelpie enters, its first ability triggers, causing you to draw a card.
7. Repeat.