Ironclad has some trouble blocking sometimes, and there are enough enemies who attack multiple times per turn that this is a valuable way to stall against those. Especially good in decks which make excess energy, which Ironclad can often do, and a nice payoff option for Stampede, although Stampede is not one of Ironclad's best build-arounds. I usually take Mangle if my deck has mediocre turns such that I think paying 3 for it could reasonably be better than anything else I have available.
