The Highlands are peppered with dozens of circular stone installations embedded in the ground at key locations created by the wizard Merlin back when he was a student at Hogwarts.
Their mini-map icon is a leaf. Dropping special leaves called Mallowsweet onto the circle activates a puzzle that you must solve. Solving a merlin trial grants the main character additional inventory slots. The following is a list of confirmed merlin puzzles and their locations:
- [first one] Lower Hogsfield, from floo flame toward the river to Nora Treadwell's camp
chest next to her camp has x5 mallowsweet
requires Incendio - due south of Nora Treadwell's camp
destroy the heads - just off the road due south of the gamekeeper hut
- just north of Keenbridge Cemetery
- just south of the windmill
- near the four stone pillars along the shore
- near the maze bog
- rocky cliff above Hogwarts school just past the bridge which crosses directly in front of a waterfall