I think the last mission was easy because the game is poorly balanced. Since walls are useless, you can simply dig huge rooms. Also, gold is never an issue during the campaign.
Sure, the scenario can backup this because we are "the choosen one", but I think that is not the purpose.
I also raise you that Medechaus could come from Mendecious (Latin not simply for liar but for "not telling the truth, deception").