Walkthroughs for custom maps.

With a Berserk hero, other heroes with fire magic can attack Madre, weakening her with hit-and-run tactics, as the town is nearby, and Madre is ordered to stay put. And when there are significantly fewer dragons left, Baltazar will be able to defeat Madre in battle.
This situation shows that bad luck with something that drops randomly can have a fatal impact on the playthrough.
I looked again: unfortunately, someone has already dug up the Grail! So, either accept it, or start over.