For some reason MB LC almost always whiffs on Doomsday despite his seemingly large hitbox. It really sucks cause I tend to feel like I should be able to use it whenever but I can't lol. Against Grundy I'm not 100% sure but I think it usually doesn't whiff but the problem about using it is that if Grundy uses walking corpse, it absorbs and beats the MB LC. The only MUs where I can use MB LC basically whenever I feel like it are against Bane and Lex.