Naphiya, Tacticus War-mage

Creatures you control get -2/+2 and have
defender.
Whenever you attack an opponent with one or
more creatures with defender, you may pay
{w/u}. If you do, look at the top three cards of your
library. You may reveal a creature card with
defender from among those cards, and put it
onto the battlefield tapped and attacking that
opponent.