Shyssa, Vengeful Warden

Flying, Haste, Trample
At the end of each opponent's end step, if a
creature they control attacked this turn, deal
damage to them equal to the number of creatures
they control. If a creature you control blocked
this turn and died, the damage is equal to twice
the number of creatures they control instead.
Regenesis 2 - {r}{r}{r}