Treebeard, Gracious Host + Scurry Oak + Soul Warden

Treebeard, Gracious Host

Scurry Oak

Soul Warden

How it works

1. Gain life.
2. Treebeard's second ability triggers, putting that many +1/+1 counters on Scurry Oak.
3. Scurry Oak triggers, creating a 1/1 Squirrel creature token.
4. When the Squirrel enters the battlefield, Soul Warden triggers, causing you to gain life.
5. Repeat from step 2.

This charming and robust loop begins the moment you gain life, which causes Treebeard, Gracious Host to place a +1/+1 counter on Scurry Oak thanks to its trigger condition. Because Scurry Oak is a Treefolk, it grows larger, which in turn fires off its own nested ability to generate a 1/1 green Squirrel creature token. That new token entering the battlefield immediately prompts Soul Warden to grant you 1 life, looping right back into Treebeard's ability to keep the cycle spinning infinitely.