Complex sentence: Another group of Phalanx later decimated the Shi'ar throneworld in the absence of the Imperial Guard, before Beast, with the assistance of other X-Men and Trish Tilby, devised a way to discorporate many of them.
Split into simpler sentences: Another group of Phalanx later decimated the Shi'ar throneworld in the absence of the Imperial Guard. However Beast, with the assistance of other X-Men and Trish Tilby, devised a way to discorporate many of them.