Following the completion of the war table operation, Specializations for the Inquisitor, three trainers will appear at Skyhold, and if the Inquisitor is a mage, Your Trainer will be one of them. She can be found in the Lower Courtyard in Skyhold when she first arrives. She was part of a team of twenty mages studying the Breach, of which she is the only survivor. Her studies allow her to specialize in a brand-new school of magic that utilizes the power of rifts in the Veil (hence the title Rift Mage). She can teach the Inquisitor this new school of magic if they are willing to learn. She disappears from Skyhold once Way of the Rift Mage is completed.
The game file for the character describes Your Trainer as, "A member of the Mages' Collective free group, she's a scattered professor of astounding ability and focus in her area of expertise. She knows so much she's forgotten common social graces," and with an appearance of "Professor stuffed with scrolls and gear for every eventuality."
She also mentions being a member of the Mages' Collective in dialog, initially recanting saying that and then saying she's proud of it.