Ambuscade

Put an Ambush counter on target attacking
creature and remove all creatures blocking it
from combat. Until end of turn, creatures that
have not blocked a creature this turn gain
"{1}, {t}: This creature deals damage equal to its
power to target creature with an Ambush
counter. Activate this ability only during the end
of combat step."
Remove all Ambush counters from all creatures
at the end of turn.