War's Exemplar

Legacy (When this card is put into your graveyard
from anywhere, exile all other cards from your
graveyard with the same name as this card.)
Whenever one or more creatures you control deal combat damage to a player, if War's Exemplar is
in your graveyard, you may sacrifice a creature
that attacked this turn. If you do, untap target creature you control, and after this phase there is
an additional combat phase followed by an additional main phase.