Nosferatu: Wrath of Malachi Hints for PC
When you get to him it is important to use the surroundings. He is almost invincible, but he does have a weakness. You should do the following: Get to a high position (above the ground), the highest place possible, then when he charges up you need to jump towards him (try to jump into him). You won't be able to do this in your first try but keep trying. Once you get inside him, just sprinkle some holy water and he will be instantly killed.
Hope I Helped!