Just gave this level a much needed update. This new version will require you to set a specific personality to your rival underlord. More details in the description.

Blue Underlord usually ends up losing all of it's units to Empire traps. Perhaps you should consider making a path so he doesn't send his entire army at Empire traps in the middle.

I meant the other way around, so that the player has to blow it up.

Actually the brimstone would make him come out quicker as it only takes one underminer blast to destroy.

Very happy that this map didn't have an Empire Keeper. How about replacing the augrum walls in front of Malleus' dungeon with Brimstone/Obsidian combo? It'd ensure Malleus won't get out before we're ready for it.