He is not on any of the three element planets. go to the asteroid belt and search for the asteroid with a building on top (after you pass all three planets!!!!). Then go in when you get the 3 knights with you. there will be a hard puzzle beat it. Than go in the room. Merlin will be there. than get the bombs and go to the ceiling exactly on top of Mordred's robot. drop the bomb 3 times on the orb. than Merlin will die. than jump on him than the chandeliers. stay in the middle if the chandelier hit him on the head do the same with the other one. if it does not than do the same chandelier again. Mordred (once robot broke) will try to get the orb, but the newly freed princess will jump on him and save all of poptropica.
With Mordred
You can't costumize him.
I think that it was Mordred.
It is next to the Mordred Museum at the entrance to the island.
In the left corner of Mordred's lair.
Mordred does not appear as an interactive character, so it is apprently not possible to copy him.
Defeating Mordred and his warrior suit wins the island, and you receive the Island Medallion and 50 Poptropica credits.
Things that Zap you on Poptropica : Lasers (Spy Island) Electrified Windows (Spy Island) Mini-Bots (Spy Island) Electric Fence (Diamond Mine, Nabooti Island) Electric Caterpillars (Jungle Planet, Astro Knights Island) Mordred's Robot (Astro Knights Island)
Twice.
There are two books in the library and one in Mordred's laboratory.
When you defeat Mordred, the game is over, and the Princess will kayo him for you. (see the related question)
Astro Knights