Sentinel is really good for the crossbones fight because he’s poison immune and has a heal block on his sp1. Claire is okay but you need to throw sp2s to get the amount of damage you need, so you’re going to die from block damage a lot. Ibom is probably okay but I’d say sentinel is better.
I haven't tried with any of them but I would suspect iBom. The power struggle node (or whichever it's called) really screws with a lot of champs that rely on SP2 or 3. Both Clare and iBom do but I suspect that iBom manages better with just SP1 than Claire does. If you happen to have willpower, he's also a healing machine.But like I said, I haven't used any champ on the list for that fight.
Rogue
Rogue I'm stacked Mutant wise and I can't see ranking her up before most of these, not if I already have a counter