Stone of Change

Found: Just to the right of the entrance to the tower of The Twelve

You can perform the following actions at the Stone of Change:
 * Adamantine Ritual
 * Attuning an item (see also: Attuned

Other "Eldritch Devices":
 * Altar of Fecundity
 * Altar of Invasion
 * Altar of Subjugation
 * Altar of Devestation