He was influencing a war between supernatural species of which I led the vampires. It was put to me that a ritual may have been able to trap him in the body of a maniac and kill him but to do that we would likely have to suffer if not die. Our blood was needed.
Back then I wasn't willing to do that. I was quite the survivalist so I used the blood of one of my men causing the ritual to fail.
He was weakened but not destroyed and a century later he returned to trouble us