This is a really bad rate for a stun effect, and it has two extra conditionals that limit its playability. Stunning is still really powerful against certain villains, but nowadays they come steady and stalwart so it's not even guaranteed to be useful. I checked and there is only one deck on marvelcdb using this card with more than two favorites: marvelcdb.com and it is a stun theme deck but Critical Hit is the worst of the bunch. I wouldn't play this card except for niche hero-scenario matchups where stunning has massive value.