Metastatic Evangel + Cloudstone Curio + Scurry Oak

Metastatic Evangel

Cloudstone Curio

Scurry Oak

How it works

1. Cast the creature by paying 0.
2. When the creature enters the battlefield, Metastatic Evangel triggers, and Cloudstone Curio triggers if the creature was not an artifact.
3. Resolve the Cloudstone Curio trigger, if applicable, choosing to return nothing to your hand.
4. Resolve the Metastatic Evangel trigger, causing you to put a +1/+1 counter on Scurry Oak.
5. Scurry Oak triggers, creating a 1/1 Squirrel creature token.
6. When the Squirrel enters the battlefield, Cloudstone Curio triggers, returning the creature with mana cost 0 from the battlefield to your hand.
7. Repeat.

This ingenious loop relies on a free creature to repeatedly trigger your board while Cloudstone Curio bounces it safely back to your hand every time a Squirrel token enters the battlefield. With Scurry Oak serving as the engine, every iteration begins when Metastatic Evangel triggers upon the free creature's entry, proliferating to add a +1/+1 counter to Scurry Oak. This counter placement immediately satisfies Scurry Oak's second ability to produce a 1/1 green Squirrel creature token, which in turn sets Cloudstone Curio's bounce ability into motion.