Half Spirit Tonic (Bound) is an item which can be used to restore 50 Spirit Power during the Underworld event.
It can not be traded or gifted to other players, and there is no way to unbound it.
Spirit Tonic (Bound) can be obtained as a Victory rewards during the Underworld event.
It is also added to the Token Box when an Battle Royale event precedes the Underworld event.
After the end of the Underworld event one Half Spirit Tonic (Bound) will be converted to one Half Power Potion (Bound).