Rowan, Scion of War

First Strike
When Rowan, Scion of War enters the
battlefield, creatures you control get +1/-1 and
gain first strike until end of turn.
Whenever a creature attacks, it's controller may
pay {1}. When they do, that creature gets +1/-1
and gains first strike until end of turn.
"The art of war is quite simple: Strike quick, and
strike hard."