I'm playing through the game again with a hero – in the ending, I complete Biar without any losses – except for Railag. He's the most "lame" hero – dragons don't resurrect, hydras are slow, chaos is good, but not for final battles... now I'll try changing the Warlock's build.
I haven't tried it, but can he reach the endgame? The spell is quite useful for the Sorceress.