This quest is not available in game.
Bring the items on Bel'dugur's Note to Keeper Bel'dugur in the Undercity.
You need Yagyin's Digest? Your plan, then, is to gather another flock? Of course it is...and of course I will help you, brother.
But you must help me too.
I require three items of power. Bring me these and the digest will be yours.
I cannot utter the names of these items, but I will write them down.
Get me the items on this list. If you can do that, then you are truly worthy of opening your own chapter of our order.