Details
Kharvos on the second floor, back left, of the large loot building called the Castle or Manor can change Mastery for a cost. [2]
Kharvos resets an ultra class through a trade, allowing the player to start over; the trade’s cost is unconfirmed. [3]
Kharvos, inside the Castle on its second floor toward the back-left side, can reset a current Mastery Oath and let the player move to another option. [4]
Location
On the second floor at the back left of the big loot building called both the Castle and the Manor. [5]
References
Community documentation; not tested in-game. Patch not stated. Sources checked .