St. Michael, the Warleader

Flying, vigilance, haste

Whenever St. Michael, the Warleader attacks for the first time each turn, untap all creatures you control. After this phase, there is an additional combat phase.

"War arose in heaven, Michael and his angels fighting against the dragon. And the dragon and his angels fought back, but he was defeated, and there was no longer any place for them in heaven. And the great dragon was thrown down, that ancient serpent, who is called the devil and Satan."
–Rev.12:7-9