Biovisionary + Storm King's Thunder + Croaking Counterpart

Biovisionary

Storm King's Thunder

Croaking Counterpart

How it works

1. Cast Storm King's Thunder by paying 2, copying the next instant or sorcery spell you cast twice.
2. Cast Croaking Counterpart by paying 1, targeting Biovisionary.
3. Storm King's Thunder triggers, copying Croaking Counterpart twice, with both copies targeting Biovisionary.
4. Resolve all Croaking Counterparts, creating three token copies of Biovisionary that are 1/1 Frogs.
5. At the beginning of your end step, each Biovisionary triggers.
6. Resolve the first trigger, causing you to win the game.