Glen Elendra Pranksters + Crimson Kobolds + Kobolds of Kher Keep + Sally Sparrow

Glen Elendra Pranksters

Crimson Kobolds

Kobolds of Kher Keep

Sally Sparrow

How it works

1. During an opponent's turn, cast the 0-cost creature in your hand by paying 0.
2. Glen Elendra Pranksters triggers, returning the other 0-cost creature from the battlefield to your hand.
3. Resolve the spell from step 1.
4. Repeat.