Tarot was drained of her life-energy by Fitzroy in Uncanny X-Men (1st series) #282. She reappeared in X-Force (1st series) #87, claiming to have truly been dead, but resurrected, and that she could not live without King Bedlam. Theories were put forth that King Bedlam's bio-electric power might have been responsible for kick-starting and maintaining the electro-chemical processes of her brain.
Tarot and King Bedlam were confirmed Decimated in New Avengers (1st series) #18. If Bedlam's powers were responsible for her resurrection, this could explain why she was dead again in Necrosha, but no official explanation was given. Also, it was confirmed in Necrosha that the T-O virus could bring the dead back to life, but depowered mutants would remain depowered, so how Tarot was able to use her abilities when resurrected is a mystery. She was eventually brought back fully through the Karakoan Resurrection Protocols.