When you antimatter one of its allied creatures, Iridium Warden will guard it. Constantly. No matter what. Even if it's been spam guarded.
Note that the dragon (which has negative attack) is delayed for 26 turns. Meanwhile, my creatures are doing consistent damage, eventually killing this deck. Yes, it has stone skin, but apparently it didn't draw them in time.
Please put some kind of check in to see if it's already been guarded, or some sort of limit on how many turns the AI's willing to delay a creature for.