Heavymaterial Dragon

(This ability is active if you have one or more face up G units in total on your or G zone):[ 1 & Choose a card from your hand, discard it, choose one of your other rear-guards, and lock it] When this unit is placed on , you may pay the cost. If you do, draw two cards. (The locked card is turned face down, and cannot do anything. It turns face up at end of the owner's turn.)