Rosie Cotton of South Lane, Devoted Druid, and Elemental Mastery

Prerequisites

• Rosie Cotton of South Lane on the battlefield
• Devoted Druid on the battlefield
• Elemental Mastery on the battlefield

Steps

1. Activate Devoted Druid by tapping it, creating at least one creature token
2. When the token enters, Rosie triggers, putting a +1/+1 counter on Devoted Druid
3. Activate Devoted Druid by putting a -1/-1 counter on it, untapping it
4. Repeat

Results

• Infinite ETB
• Infinite creature tokens
• Infinite +1/+1 counters on most creatures you control
• Infinite green mana