You start beneath the tube. As this is a Nightmode-only map, you can't see where the cheese is. Work your way to the right and jump above the pit. You will get to a platform which you can Wall Jump onto or wait for the shaman to build a ramp. After getting to this point, don't go into the tube, for it is there to confuse you. Wait for the shaman to build a ramp above the tube. The cheese is above the left end of the tube; you should wait for the shaman to help get the cheese.
It IS possible to walljump up the tube ceiling's end , but it may be difficult.
The shaman starts at the same place with the mice. Jump above the pit and build a ramp to let the mice climb to the platform. You can prevent the mice from getting trapped by using the arrow on your position quickly after you are up on the ramp. Using the chat is also advised. Next, you should build a ramp to get above the tube. After getting to the cheese, use spirit or build some sort of stairs to help the mice get to the cheese. It is recommended to block the pit before getting to the cheese, to avoid more mouse deaths. Another way to complete this level is to ghost a platform with a red anchor in the beginning and attach a ramp to the left of it going up and slightly diagonal to the left. Mice may climb up this ramp and walljump directly to the place under the cheese (full-screen suggested- you will be forced to walljump off the screen's view). The shaman can then spirit the mice up to the cheese so that they can return to the mouse hole quickly by falling through the left side and airjumping into the hole.