Still working my way through Spec Ops and have just "discovered" (i.e., read a forum post) about taking on bosses and mini-bosses at the same time, which I never knew was an option. Feel kind of stupid now. Anyway. In the interest of saving those rare unstable Isos, I've been trying to do just that while I'm on my three-star adventure.
Question: attempting to take on Mephisto and Baron Mordo at once feels like a suicide mission. I don't have any special weapons (besides the ones you get for completing Spec Ops 4 tasks), nor do I have a stellar roster. I took out Mephisto relatively easily the first time through, though I nearly emptied my healing stash, so I think it might be doable. But I also don't want to waste iso I can't spare if I'm just going to get my head handed to me.
For those of you who've done this, did it make Mephisto much harder to defeat? I don't suppose there's any chance he'd kill off Mordo like he does his other lackeys, eh?