Angelus is arguably the most powerful antagonist in the Caster Chronicles series. He is killed by Ethan Wate in Beautiful Redemption. He is a Keeper of the Far Keep. He was born a Mortal and he always wanted to be somethng more. As a Keeper his task was to write down history and not to change it and he couldn't accept that. He wanted to be a Caster so he used the blood of innocent Casters to change himself into something which wasn't entirely Caster but not really mortal either. He stole the blood of a powerful Light Telepath and used it to make himself more powerful which gave him the power to read mortals' mind. Eventually, she went mad through experiments and blood transfusions performed on her and he then destroyed her. His biggest aim was to kill the whole population of mortals as he seemed to think that they don't have the right to live. Because of him the Far Keep became corrupted. He would have done everything to end the mortal race and he was close to it after the Seventeenth Moon. However, when Ethan sacrificed himself the New Order saved both the mortal and Caster world. When Ethan went to the Far Keep to steal his page from the Caster Chronicles, Angelus tried to stop him. Ethan commented that Angelus was mortal to which he denied. Angelus fell in the pool and thinking he was dead Ethan went to get his book out of no where Angelus comes up and tries to stop Ethan. Ethan destroyed Angelus' page which killed him.
After he stole the blood of a powerful Light Telepath, he gained the power to read mortals' minds. When John Breed absorbed his powers, a flash of lightning appeared. It is unknown what other powers he gained after all the experiments and blood transfusions.