Prerequisites: Alchemist’s supplies proficiency
As an action, you can expend a Maneuver Die and use alchemist’s supplies to craft one vial of Alchemical Oil, choosing acid, cold, fire, poison, or lightning.
This vial retains its potency until the end of the next long rest, but you can’t regain your Maneuver Die until this Alchemical Oil is spent.
With the Use an Object action, a creature can apply the vial of Oil to a weapon, expending it. For the next 10 minutes, the weapon deals the damage type of the Alchemical Oil in place of its normal damage.