This quest is not available in game.
Speak with Talionia in Silvermoon City.
One of your masters, Talionia, in Silvermoon City has sent a summons for you, <name>. I'm certain it is time you learned to summon and control a more powerful demon, so I suggest you see her at once. I understand Talionia is found in The Sanctum, a cozy little den of evil found along Murder Row.