CONTAINS SPOILERS

To gain access to Haligtree, you need both Left and Right halves of the Secret Medallion to operate the Grand Lift of Rold (Switch action to Hoist secret medallion). The Right medallion is located in the Village of the Albinaurics. Break the pot nearby the large fire to reveal an old man that gives it to you. The location for the Left medallion is in Castle Sol after defeating Commander Niall.