shuffle it into the Deck, or, if you control no monsters, you can add it to your hand instead
Well, or at least that used to be the case
Massacre Wurm's first ability affects only creatures your opponents control at the time it resolves
Once per turn, if you control no other monsters: You can Special Summon 1 "Noble Knight" monster from your Deck in Defense Position, except "Noble Knight Medraut", and if you do, destroy 1 Equip Spell you control
Archangel Avacyn / Avacyn, the Purifier At first glance, Archangel Avacyn looks like a simple flash flier that gives your creatures indestructible when it enters
Each time your opponent shuffles their hand back into their deck for this reason, you may draw an extra card