I have found the Ring of Calling and released it from the arm, but then what. I know I shall bring it to the Seal of Mythandor, but where excactely is that???
Second, where do I get the word to open the "cruel" seal and the "song" seal?
The Seal of Mythandor is in the NWern corner of the Hall of Lights. You have to fight a few enemies on your way and inside the area. Once they are dispatched, the seal will open and transport you out to the Speculum Grounds.