1. Go up through the yellow teleport.
Make the monsters go up, too.
2. Go down using the red teleport.

Bring the monsters to this position.
One on top, two below.

Now guide the monsters to the left.
The top monster can be used to explode the bomb.

1. Bring 2 monsters to the bottom by using the red teleport.
2. Guide 1 monster to the bomb which contains the mystery.