Walkthroughs for custom maps.

Well, it's not like it completely prevents you. You can teleport to that zone as soon as possible and take the army. And if you generate a bunch of demons there, you can get a very powerful hero quite early. I'm too lazy to check myself, but it seems strange that the computer doesn't attack if you stand in the portal. Maybe it's some kind of bug due to HD+ or a specific version of SoD_SP?

I agree, we get the gameplay points much earlier than we reach the castle, and that's already critical. At this stage, such a group of dragons can be quite helpful. But again, I agree with obi; I don't see the point in using this opportunity, otherwise, what's the point of playing such a challenging map if you can bypass the author's intention? It's like completing the rotk wenwell map due to the author's oversight; it's interesting, but it's hard to consider it a full playthrough.