This level starts off weirdly. Your Heart is isolated from the rest of your dungeon, which means you could be invincible. The destroy walls spells is hidden inside the small hero fortress so Blue is unlikely to ever get it.

That being said, that's boring and it bugs creatures so I opened the way to the gold and left the left side fortified in case hero parties come this way. Spoiler alert: they won't as there are no parties on this map except for the very final one. Your dungeon is connected to the massive gold line across the map all the way to Blue's dungeon, so turtling is not an option in the long run. Blue came at me fast but stopped at the gems in the middle which gave me time to catch up to him. I threw away a lot of demonspawns so I was quite behind in creature numbers, but Blue doesn't get any advantage except for a scavenging room right off the bat. Also he can build workshops while you can't until you claim one.

After that, a single battle later and Blue was gone. I then went for the heroes which were considered the "dangerous part" by the mapmaker and found that they were disappointingly weak. Destroying the Heart doesn't end the game though, as you have to keep going left to find a small hidden room with the destroy walls spell. That triggers the final party in a single slab hidden behind a dirt block left of that, where I fought a bunch of Knights of all levels with an Avatar.

2/5, nothing special and mapmaking mistakes such as the isolated Heart in the beginning. By the looks of it I think you were supposed to defeat the heroes first and then the enemy Keeper, but with keeperfx basic AIs are agressive and the more urgent threat is Blue.