Moritte of the Frost + River Kelpie + Phyrexian Altar

Moritte of the Frost

River Kelpie

Phyrexian Altar

How it works

1. Activate Phyrexian Altar by sacrificing Moritte of the Frost, adding one mana of any color.
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 two +1/+1 counters on it and one -1/-1 counter on it.
3. Remove one +1/+1 counter and one -1/-1 counter from Moritte of the Frost as a state-based action.
4. When Moritte of the Frost enters the battlefield, it and River Kelpie's first ability triggers, causing you to draw two cards.
5. Repeat.