Agroth, the Beheader

Haste, menace, behead (At the beginning of each
end step, put a +1/+1 counter on this creature for
each creature that was was dealt lethal damage by it
this turn.)
Whenever Agroth, the Beheader attacks, each
other attacking creature you control gets +1/+1
until end of turn for each +1/+1 counter on
Agroth.