Worshipper – “Agral’s Decision” [Campaign 2, Mission 5]

First, enter the cheat code add_all_spells, then cast the "Astral Gate" spell and pass by the dragons. It's simple.

Well, firstly, it's cheating. Secondly: in versions higher than 1.3, cheats don't work. And thirdly: it's such a minor thing that using cheats can ruin all the previous campaigns because it makes changes to the game's structure.