Nigon, because it resembles him more than the Dungeon, and so people know that this is a modified (for all known reasons) castle from the third game). IMHO... and I haven't come up with another name yet)))
regarding the creatures...
I added others because the original ones were removed. And hydras weren't in Nigon, by the way; they were only in the second and first parts, but there were Warlocks, not Nigon.
Rooks don't fit... what are they doing underground? )
and why not make a second Dungeon? Is it impossible for anyone else to be there besides the Dungeon? I want more variety, and also creatures from previous Heroes games... at least a few. And the other mobs (from other games) are a good addition. IMHO
PS and I made a slight mistake with the name. I wanted to write Nigon - the second underground race, not the second Dungeon... because this is not a replacement for the Dungeon.