Inhumans Vs. X Men by Charles Soule

When the Inhumans' Terrigen Mist is revealed to be lethal to mutants, desperate measures lead the two communities into open conflict: mutant leaders push to eliminate the environmental threat that is erasing their people, while Inhuman royalty fights to preserve the ritual that defines their society. The escalating battles force friends and allies onto opposite sides, produce wrenching moral choices and sacrifices, and probe whether survival can justify violence or whether coexistence is still possible when two species see the other as an existential threat.