Sharuum the Hegemon + Mirrormade

Steps

1. Cast Mirrormade by paying {1}{U}{U}.
2. Mirrormade enters as a copy of Sharuum.
3. Put Sharuum into the graveyard due to the legend rule.
4. Mirrormade triggers, returning Sharuum from your graveyard to the battlefield.
5. Put Sharuum into the graveyard due to the legend rule.
6. Sharuum enters the battlefield triggers, returning itself from your graveyard to the battlefield.
7. Repeat from step 5.