Question: Is this the same Nikoli that escaped the Reckoning from Heroes of Might and Magic IV and mentioned in Might and Magic IX or is this a completely different one? I tried looking it up online but couldn't find anything and no. I haven't played Heroes of Might and Magic IV as I haven't bought it yet and I haven't been able to play Might and Magic IX because of how buggy and confusing that game is.
Heroes1-4, and Might and Magic 1-9 was developed by New World Computing. After 3DO (who owned NWC) got bankrupt around 2003, Ubisoft bought the rights to the Might and Magic franchise. They made (well Nival did, ubisoft only published) Heroes 5 and later on H6-7 and MMX. The old New World Computing games (called by fans the Ancient universe) and the newer Ubisoft games (called by fans the Ashan universe) are in a different universe, there are no story connection between them.