Tower Defense is a module in which mice must get the cheese, passing through many towers to do so. However, unlike a normal map, the shaman's job is to place towers to impede the progress of the mice in acquiring said cheese. The first spawn is at 2:50, the next is 2:20 and every 20 seconds after (2:00, 1:40...).
When a mouse is shaman, they may move the camera around the map similar to if they had died. From there they can place and rotate arrows to shoot different projectiles.
Once you select a tower type, every arrow (tower) you place after that will be of that type until you change it again. You start of with 12 points and slowly regenerate over time.
All towers activate after a set amount of time all at once. They also reuse their ammo, so if there is a cannonball rolling around, it will be teleported back to the original tower and shot once again.
The objective of a mouse is rather straight-forward, if not easy: get to the cheese (it is not necessary to get it back to the hole). If you die in the process, you will re-spawn shortly after in the next "wave". Every mouse in that same wave will have their name printed in that colour above their heads. After you respawn, you get a double jump. Press up then space in order to jump twice. Each consecutive wave has a stronger double jump, meaning you jump higher after pressing space. The goal is for to get 1 cheese for every mouse in the room (shaman excluded). If 3 or fewer are present, the goal is 3. Every mouse is encouraged to get the cheese as many times as he/she can (You DO get cheese for reaching the cheese).