Sentinelspire

The Fortress of Sentinelspire looks down from the canopy of the world, ready to sow the seeds of destruction.

Death flows from the Fortress of the Old Man hidden in the canyons of Sentinelspire, a vast and dormant volcano. The secret paradise of Faerûn's most dangerous assassins, the Fortress specializes in high-profile murders that leave no witnesses.
But with the powers of an archdruid at hand, the mad master of the fortress will bring death to more than just the enemies of his patrons -- he will call down doom on all of Faerûn.

Sentinelspire has been waiting to complete the cycle.