This magic green gem can be found in the lumber mill after defeating Shia LeBeouf and his wolves. The gem will glow when the right person wields and its powers will be unlocked for that said person, and that person alone.

When you wield this stone, for a brief period, you can slow down time for your self. It will allow for the user to have double movement and one additional action. The stone can also be used as a reaction, so that you can escape an incoming attack.  

Notes: Advantage: Spell Attacks, Advantage: Ranged Attacks, Advantage: Melee Attacks, Advantage: Choose a Skill