Bastion, the mutant-hating cyborg from the future, has used a specific kind of alien techno-organic or "T-O" virus to revive many of the X-Men's ennemies, including the villainour Leper Queen, Donald Pierce and others. The T-O virus allows him to control those he reanimates but the minds of the undead remain intact, leading them in some cases to fight back against his control. But Bastion's hold is too strong and the members of his cabal are unable to free themselves from his influence. What he has planned for the X-Force team and mutantkind remains unclear at this time...

One of the men that helped Bastion to locate the alien virus is a vampire named Eli Bard who upon discovering the virus, became infectied with it. Eli then broke with Bastion, bringing the newfound technology to his master, the mutant Selene, a psychic vampire possessing the ability to psionically drain organisms of their life force. Selene has used mysticism to pervert the T-O virus and, with her new inner circle at her side, has set a plan in motion that no one will see coming until it's too late...

Collected in X-Men Milestones: Necrosha.