World 2 - Level 2
Prism, Prism, on the Floor

Bring Stinky counter-clockwise to the antechamber using the Prisms. Once arrived, push the prism along the first green arrow up. Carefully collect the coins and push the reflector along the yellow arrow. Switch to Loof to destroy both wood boxes. Now push the prism along the second part of the green arrow to destroy the first box to the right. Drop the second box into Lava, retrieve the second reflector and move it along the light blue path. All rainbow coins will now be accessible.

To collect the bonus coins, use the two steel boxes in purple and push them into the lava along the purple arrow. To do so you'll need to position one of Stinky or Loof at the purple "X".