The Draught of Mind Rebirth is a consumable that resets Coen's abilities so you can spend the points again. It arrived with Update 1.1, so you can now fix a build you regret.
It refunds the abilities you have learned so you can rebuild Coen. Use it when a tree is not working for your play style.
Check Anca's trade menu first. The Matriarch in Uriash Village and other Witchcraft vendors such as Vera are also reported to stock it, though one player found none at the vendor outside Svartrau. Whether you can buy more than one is still unconfirmed.