With KeeperFx 1.3.1.4778 , this campaign seems to work very well . So I try to write walkthrough of this campaign (sorry for my poor english).

Overview - In this campaingn, in most level you can use strong creatures like dragon, mistress, vampire. But in most cases monster snowballing is not allowed, there are some limitaitions on the types of rooms, traps, and doors can be build, as well as money and time. So the selection of your minions must be made carefully and quickly. Each level has its own gimick, and understanding it is the key of victory.

(1) Swedish spirit - This level starts with Steal Hero special box. You can get one of the following three creatures ... troll, warlock, orc. And depending on which one you chose, which room you can build and which creatures you can get is decided. Orc may be easist, cause you can make LV10 skeletons as you like. Troll has no money problem. Warlock might be hardest, but you can attract some dragons in addition to warlocks.

(2) The Nameless Hero - Relatively ordinary level. You can get prison and torture chamber as you proceed.

(3) Invisible - In this level invisible thieves try to steal your money, so measures will be needed. If there are no gold pile in your treasure room, they can't steal your money. Instead they will attack your dungeon heart, but run away immediately when attacked. If annoying, you can fill their intrusion route with lightning traps. You also need to limit the number of working imps to just one (for not collecting fallen gold without permission). Dellayed payment? Ask creatures to be patient in the temple. In later game you get access to graveyard and gem, and the threat is over.

Apart from thieves, there are regular hero party invasions. Getting stronger but not infinitely spawning, maybe you shouldn't go out into the open south space early. But if you can survive last invasion (LV10 dwarfx3, samuraix3, witchx6, but no closing invasion message), after that conquering the hero dungeon room by room from southeast entrance is not so difficult.

(4) Embattled formation - VS three keepers formed an alliance. If there is a stable strategy in this level, it is to train and possess the Warlock, and shoot fireballs. But you have to defeat two of the three enemy keepers at the same time. Otherwise surviving two enemy keepers will get free reinforcements a little after. If you are not good at FPS, you might want to skip this level.

(5) Okehazama - After a long time, suddenly lots of LV10 heroes will spawn from hero gate and pour into your dungeon. But there is cheap trick to prevent intrusion. Build temples on the waterfront. It works like a one-way door. I doubt it was intended, but heroes doing the same thing with guard posts.

Though you can't build bridge on this level, you can occupy the green and yellow enemy keeper area along the road on the edge of the map. You can find "destroy walls" spell at green keeper's library. Using a ghost and this spell to connect yellow keeper's area to hero gate may be a good idea.

(6) Twin keeper - Beautiful symmetrical map with strong two enemy keepers formed an alliance. As the info message said, initially enemy twin keepers prioritize fighting heroes and don't actively attack you. Therefore it doesn't seem difficult to secure both left and right gems, by then it may be too late. Cause the biggest events on this level will be activated when hero's dungeon heart is destroyed. A neutral LV10 avator and four LV10 knights are released. Unoccupied scavenger room are revealed. And a "disease" spell is lying on the ground. You must get all bonuses before enemy twin keepers. For that it might be easier to use possessed LV3 imp. After successfully retrieving everything, the trench warfare begins in the scavenger room. But if you can maintain this room, the tide of battle will gradually towards victory. With not so tight restrictions, it's well-balanced and suitable for the final level.

I don't know how to beat 3rd lvl.

I enjoyed this campaign. It is short one with just 6 level. Level 4 didnt really fit well with rest of campaign in my opinion. It would be much better to be use it as Secret level. Last level was also too short for me, becase of of the keepers got destroyed by heroes and I think I was supposed to fight both of them. I really liked the choice you have in first level and otherlevels has some interesting things and are done nicely. Quality of campaign is somewhere between 3 and 4 for me., difficulty is 3-4 from 5.