Kepra, Pride of the North

Defender, first strike
When five or more Human, or Knight creatures
you control attack, if it's the first combat phase
of the turn, untap all attacking creatures. After
this phase, there is an additional combat phase.
If five or more other creatures you control go to
your graveyard this turn, put five +1/+1 counters
on Kepra, Pride of the North and it loses
defender.