ELECTRIC STEEL
You reach a locked door with an electric eel on either side. One is friendly, the other is mean. How will you get through the electrified exit?
Solution:
Use armour, swords and metal items to connect the two eels (completing a circuit)
Hold hands and touch the eels to open the door
Use dead bodies from local monsters to connect the eels
Notes for DM:
Spice things up by electrocuting any players who touch the door or the eels.