Second Avalon
Avalon is also the name of a fictional planet in the 30th century of the DC Universe, named after the legendary island. Ruled by a king and served by knights bearing weapons shaped like oak branches, the planet exists in a medieval stage of technology.
The King's rule is challenged by a wizard calling himself "Lord Romdur", who turns out to be Mordru in disguise. The Legion of Super-Heroes visits the planet, where Star Boy uses his mass-inducing powers to collapse Mordru's castle, burying him alive. He remains there until freed by Darkseid.
Read more about this topic: Avalon (DC Comics)