As I have already stated, there are too many "greater" monsters that don't exist in monster manual.
It was probably easier to make them than creating a new monster that would require new animation and sounds.

Well, I think it is time to change them.
I haven't decided exactly what they will be but below my ideas:

- Greater Wyverns (Durlag Tower) : Dragon (one to replace all 3 wyverns) . This encounter was designed to be fight with the whole charmed party. 10-12 characters is perfect for an heroic battle, and with ancient wyrm skeleton, dragons are a good choice. I'm considering an Adult Chromatic Black Dragon (14 hd).


- Doomsayer (cursed artefact): It doesn't exist in P&P and is just a modified battle horror. I think a Stone Golem would be good. But he wouldn't come from nowhere, he should be near artefact, turning hostile once it is stolen.

- Crypt Crawlers (Durlag Tower): no idea yet

- Greater Ghoul (Durlag Tower): Spectre. It could be a good alternative : fast and level drain

- Named greater ghoul (Durlag Tower): Ghoul Lord