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

Cards

All permanents on the battlefield (
Moritte of the Frost as a copy of
River Kelpie).

Activate
Yahenni by sacrificing
Moritte of the Frost.
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.
When
Moritte of the Frost enters the battlefield, it and
River Kelpie's first ability triggers, causing you to draw two cards.
Resolve the
Yahenni ability from step 1.
Repeat.