Mendechaus and Kira are fighting in a Forever War
- They use Underlords and Overseers as pawns in an eternal fight to best each other. Whenever an Overseer or Underlord is banished from the material realm, they will automatically switch allegiances
Mendechaus and Kyra are neither good or evil
- They truly possess Orange And Blue Morality.
Underlord Draven is indeed the same one from League of Legends
Mendechaus is actually the Mentor from Dungeon Keeper
- Either he can travel through dimensions to mentor to aspiring world conquerors, or Dungeon Keeper and "War for the Overworld" share continuity.