No, because the Witch can't take pieces. The king is never under threat.
Bulldog Endgame Theory
Here's the basic idea...
white to move, mate in two...
Right, this is mate. But like I stated before, it's impossible to actually get here if black plays well. White can't force the king to the corner.

I'm not actually sure. The witch might actually come to black's rescue here, because white cannot put black in zugzwang.
If it's K+N+N vs K, then the knights can force the black king into the corner, they just can't force checkmate, they will stalemate the king trying.
In this case, we maybe shouldn't even think of the witch as a piece. Instead, it's a free tempo that stops white from being able to push the king back.
Yeah, it might well be. The theory of it is saying that it should be drawn but I haven't looked at anything concrete

Hmm there is perhaps one resource that black has... he can use his witch to block a knight, since I cannot capture (unless it's a checkmating move of course). I think white is winning by force here if black centralises his king and then wastes moves with his witch when not in check, but if black uses the witch to deny my knight good squares, that might be enough to draw.

This may sound bizarre, but I believe two bishops vs a guard is a win for the bishops.
No chance.

This may sound bizarre, but I believe two bishops vs a guard is a win for the bishops.
No chance.
The bishops have the ability to separate the king and guard by putting them on cross-hairs. I don't know if they can also push the guard back so the king can invade.
This may sound bizarre, but I believe two bishops vs a guard is a win for the bishops.
That actually sounds feasible. I'm not sure if it is or not though. Do you have lines or anything?

This may sound bizarre, but I believe two bishops vs a guard is a win for the bishops.
No chance.
The bishops have the ability to separate the king and guard by putting them on cross-hairs. I don't know if they can also push the guard back so the king can invade.
Assuming the guard is already close to the king, I can't see how the bishops can forcefully separate them. Once the guard is blocking checks, it's easy for black to hold.
I think, anyway.
How about K+N+N vs K+W?
Gotta be a draw, the witch can sacrifice itself every turn, since 2 knights vs. king is draw.
Well this is an interesting one. I know K+N+N vs K+P is often a win. I think it would be a draw, because white always was to act with checks. What I mean by that is that while with a pawn, white can block the pawn, with a witch you can't. So I believe it is drawn.