Back To Gloom Keep by Ankh
Ankh took the map source for e1m5 and quothified it. Quoth monsters, some nice new effects using Quoth features and some twists you did not expect. Head over to func to comment and drop a demo of your playthrough.

Download e1m5quoth.zip (1 Megabyte, e940685a88502fafec324add5df012cf). Obviously you need to have Quoth (Quaddicted Entry) installed.