Complex sentence: When Phoebe has a terrifying premonition of Prue being stabbed to death, Prue takes the drastic step of saying an incantation to multiply her strength and the spell surprisingly results in the creation of two additional Prues to fight the enemy, a reincarnated ancient Lord of War.
Split into simpler sentences: When Phoebe has a terrifying premonition of Prue being stabbed to death, Prue takes the drastic step of saying an incantation to multiply her strength. The spell surprisingly results in the creation of two additional Prues to fight the enemy, a reincarnated ancient Lord of War.