Cleric Class + Trostani, Selesnya's Voice + Scurry Oak

Cleric Class

Trostani, Selesnya's Voice

Scurry Oak

How it works

1. Gain life.
2. Cleric Class triggers, putting a +1/+1 counter on Scurry Oak.
3. Scurry Oak triggers, creating a creature token.
4. When the creature token enters the battlefield, Trostani triggers, causing you to gain 2 life.
5. Repeat from step 2.

This loop uses Cleric Class and Trostani, Selesnya's Voice to turn any initial life gain into a self-sustaining engine. Every time you gain life, Cleric Class's level 2 ability places a +1/+1 counter on Scurry Oak, which in turn triggers Scurry Oak to manufacture a fresh Squirrel token. That token's arrival lets Trostani, Selesnya's Voice trigger and hand you life equal to its toughness, feeding right back into the Class to keep the whole process spinning infinitely.