The Phoenix remained with the X-Men for only a short time. She prevented the complete destruction of the universe by repairing the damaged energy matrix at the core of the M'Kraan Crystal. During a skirmish with the X-Men's first and most deadly foe, Magneto, Phoenix and Beast were separated from the other X-Men, with each group believing the other to have perished. In Greece, Phoenix met a young and handsome man named Nikos, later revealed to be Mastermind, a mutant with illusionary powers. He began to plant seeds of dissent within Phoenix's fragile psyche by comparing her to a god and insisting she can do whatever she wants. She would later encounter him again in Scotland, under the guise of Jason Wyngarde, a handsome 18th Century loyalist, believing him to be both the work of the reality-warping mutant Proteus and the lover of one of her ancestors.