I just had an idea to address this problem:
1. Asterix goes down the telepher as normal.
2. He goes up the stairs and encounters formations blocking the pressure plate. He grabs the fire on the other side of the door
3. He goes down to the breakable wall and ignites the powder keg.
4. Behind the wall is a potion dispenser. Asterix uses the potion to rid of the formations!
Ideas???