Heroes (Or villians as it were) can be random or set, Tiberius has haunted the cemetery for the last three games for me, there a giant in the Freedorn island who I believe is also set. Other villans inhabit roughly the same area, I just fought Hue (A beholder!) ,last time he was by the dwarf castle past the metal grate, this time he was by Gerda's castle, Ruin Guy was in the underground cave last time and this time at the exit to the same dungeon so roughly the same area. I love the way the devs thought about their spells and stratergies, Hue teleport's his massive spider stack's in the midst of my archers
and Tiberius cast Book of Evil which fits his little background story - great job!