Radimus Erkle is the Grand Vizier of the Legends' Guild and is in charge of admissions into the guild. He is also the brother of Siegfried Erkle, who owns the Legends Guild Shop of Useful Items.
He will send players off to complete the Legends' Quest as proof that they are worthy enough to enter the guild.
Erkle is the solution to the master anagram clue: Mus Kil Reader. He will ask you to solve either a light or puzzle box.