Trexum, First of the Forge

Haste
Whenever Trexum, First of the Forge attacks,
reforge 8 (You may exile another permanent you
control. If you do, reveal the top 8 cards of your
library and put a permanent card with equal or lesser
mana value than the exiled card onto the battlefield.
Put the other revealed cards at the bottom of your
library in any order.)
Whenever you reforge, you may return target permanent card you own in exile to your hand.