Scourge of the Throne [Murders at Karlov Manor Commander]

Flying, dethrone (Whenever this creature attacks the player with the most life or tied for the most life, put a +1/+1 counter on it.)

Whenever Scourge of the Throne attacks for the first time each turn, if it's attacking the player with the most life, untap all attacking creatures. After this phase, there is an additional combat phase.