Horde Frontier

Whenever Horde Frontier attacks you may pay {x}{g}if you do return X creature cards from your
graveyard to the battlefield tapped and attacking.
Sacrifice them at the end of combat.
Whenever a creature with power greater than
Horde Frontier enters the battlefield under your
control, Horde Frontier gets +1/+1 until end of
turn.
"Kill me, I'll come back tomorrow."