[quote=@liferusher]
<Snipped quote by Sir Lurksalot>

How would one go about killing him
[/quote]

Well, at his current strength, knives can cut him but they're not gonna do much good, swords and axes WILL cut him and cut him deep, though it may take a bit more chopping than usual to actually put him down.

He doesn't really have a counter to magic, however, so using it set him on fire would probably kill him at any level just as easily as anybody else.

Or drowning him.

Or poisoning him.

Or starving him.

Or suffocating him.

Or making him bleed out. 

Or electrocuting him.

Or infecting him with magic-murder-rabies.