Arthen, Merciless Vigilante

Vigilance, Double strike, Reach
Whenever a creature enters the battlefield, its
controller chooses for you to deal 3 damage to it,
or for you to give +5/+1 to target creature you
control.

"Just as my ancestors, you will die by the rage and
vengeance of your opponents. The only difference
is, unlike my people, your horrid tribe will not be
alive to tell of your demise."