Uncanny X-Men (1963) #534

The X-Men have an infectious, killer disease. What could possibly mean enough to make them break quarantine and risk exposing the world? And when that plague cuts them off from their powers, what would be the use of doing so anyway? Cyclops has his answers. You can make up your own mind. Meanwhile, Emma Frost and Sebastian Shaw finish their physical debate... and the final words will change their relationship forever.