I read EXM #1 and #2 and I feel like I'm clearly missing some background. I lapsed during Secret Wars. I have recently caught up on that mini-series, but I didn't touch the spin-offs. Nor have I read anything Inhumans. I also did read UXM #600 and there seems a big gap between that issue and EXM and the new UXM.
I don't really understand why the Terrigen Mist is only an issue now when that happen so long ago in Infinity. Apparently lots of mutants have died such as spoilers:end of spoilers, who seemed fine in UXM 600, which is why I feel like I'm missing something I should've read.
Cyclops