Armed Instructor, Bison

(This ability is active if you have four or more damage):During your end phase, when one of your Great Nature rear-guards is put into the drop zone, choose up to two cards from your damage zone, and turn them face up. : 2 Choose one of your Great Nature rear-guards, and that unit gets +4000 until end of turn, and at the beginning of the end phase of that turn, retire that unit.