Moritte of the Frost + River Kelpie + Yahenni, Undying Partisan

Moritte of the Frost

River Kelpie

Yahenni, Undying Partisan

How it works

1. Activate Yahenni by sacrificing Moritte of the Frost.
2. When Moritte of the Frost dies, its persist ability triggers, returning it from your graveyard to the battlefield as a copy of River Kelpie with one +1/+1 counter on it due to its persist ability and its static effect.
3. When Moritte of the Frost enters the battlefield, it and River Kelpie's first ability triggers, causing you to draw two cards.
4. Resolve the Yahenni ability from step 1
5. Repeat.

This loop turns the graveyard into a bottomless well by exploiting Moritte of the Frost's clever ability to enter the battlefield as a copy of River Kelpie. Because River Kelpie triggers whenever another permanent enters from the graveyard, and its own persist ability keeps feeding it back into play with a -1/+1 counter that instantly cancels out with Moritte of the Frost's own bonus +1/+1 counter, the copying creature can die and return endlessly. Yahenni, Undying Partisan acts as the willing executioner for this cycle, using its sacrifice outlet to trigger the persist chain while also granting itself protection along the way.