Gyruda, Doom of Depths + Mortuary + Clever Impersonator

Gyruda, Doom of Depths

Mortuary

Clever Impersonator

How it works

1. Cast Clever Impersonator by paying 2, having it enter the battlefield as a copy of Gyruda.
2. Put Clever Impersonator into your graveyard due to the legend rule.
3. Mortuary triggers, putting Clever Impersonator on top of your library from your graveyard.
4. Clever Impersonator's enter the battlefield ability triggers, causing each player to mill four cards and you to return Clever Impersonator from your graveyard to the battlefield as a copy of Gyruda.
5. Repeat from step 2.