Kurloz doesn't realize at first that he's broken his vow of silence and keeps sending spell after worldless spell at the boggart, just yelling with uncontained rage with each lash of wand. The skin and muscles are completely disintegrated from one arm, large jagged stitches sew the thing's mouth and eyes shut, bones are audibly heard wetly cracking into pieces inside it's body.

At Murdoc's prompting Kurloz turns with a snarl twisting his features, glaring at the professor for a moment with wild eyes for daring to interrupt him serving some RIGHT AND PROPER MOTHERFUCKING JUSTICE. His mouth splits in a feral grin and he whispers, voice rolling deep and thick like smoke:

"Not yet."

As he keeps tearing into the thing and whittling it down into a pitiful mess on the floor, he distantly registers that the laughter hasn't stopped, but doesn't realize it's coming from him now.

Finally, when the boggart's a quivering mess on the floor, Kurloz grins viciously at it and flicks his wand, silently casting Riddikulus and sending it disintegrating into smoke and swirling back into the safety of the cupboard.

In the silence of the aftermath he stands there breathing heavily, exhilarated and still grinning with triumph.