"'Tis but a flesh-wound..."

One might call him a phantom.

Except he can't hold on with a toughness boost like phantoms.

'tis but a scratch!

Is this supposed to be a reference to the Black Knight from Monty Python who gets all his limbs cut off?
Because this doesn't feel like a monoblack card. The "attacks each combat" is red and "prevent the damage and remove a +1/+1 counter" effect is white.

This is like a Red/White or Red/Green card. And while I get the move from “Black and red are differentiated by can’t block and must attack” to just “must attack” I really don’t see that last ability swotching to Black.

Unbreathing Horde I don't think it is that strange for black. If it had a way of getting indestructible (or regenerate) instead of preventing damage would it feel black? This is basically the same thing but less complicated.