On the rock in the middle of the lava flow there should be an elemental with the title "The Wounded" under its name. It is is a ^^^80 heroic mob. Use Query Element then Dominate Element and it will aggro. Kill it and retrieve your item off the body.
Return to The Apprentice
This quest is part of the Conjuror Epic Weapon Timeline, and can only be started/completed by a member of that class of at least Level 80.