Complex sentence: This was the team created by Magneto in an alternate timeline after Xavier was killed in early life in the episode "One Man's Worth," in which the humans and mutants were locked in a war.
Split into simpler sentences: This was the team created by Magneto in an alternate time-line, after Xavier was killed in early life, in "One Man's Worth" episode. In "One Man's Worth", the humans and mutants were locked in a war.