Phyrexian Altar + River Kelpie + Hardened Academic

Phyrexian Altar

River Kelpie

Hardened Academic

How it works

1. Activate Phyrexian Altar 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. Hardened Academic and River Kelpie trigger.
4. Resolve the Hardened Academic trigger, putting a +1/+1 counter on River Kelpie.
5. Resolve the River Kelpie trigger, causing you to draw a card.
6. Repeat.

This clever loop lets you feed River Kelpie to Phyrexian Altar for mana, triggering its persist ability to bring it right back to the battlefield with a -1/-1 counter. Because the Kelpie leaves your graveyard in the process, Hardened Academic's passive triggered ability swoops in to place a +1/+1 counter on the Kelpie, neutralizing its -1/-1 counter through state-based actions. At the same time, River Kelpie's own graveyard-entry trigger goes on the stack to draw you a card, setting up a self-sustaining cycle of sacrifices, counters, and card draw fueled by the Altar's mana.