Storming the Sewers requires 2 RotV (or 1 RotV plus booster pack terrain) and 1 SotM (flexible if using 2 RotV). Gameplay is objective-based. Designed for 2 players, but can be adapted to 4.
You forgot to mention the Castle with the requirements
I like the map very much, it is small and crowded and that's cool. What I do not understand is the scenario. The high tower is only reachable by flying creatures, and why would flying creatures first dig a tunnel for three months instead of flying directluy to the high tower? Or sgt Drake, and we could find a way to stop Drake from getting on top of the high tower, as he has enough lives to leave engagement and you cannot shoot him out of the tower because he has thorian speed.
Oh and the way you use ladders to keep the two levels steady is really nice!