Bottle of Shadows

The bottle initially has 4 charges.
When turned upside down, the bottle summons a shadow
to do the bidding of the user, draining 1 charge
each round of service. As a standard action,
the bearermay dismiss the summoned shadow.
If the shadow kills a humanoid creature
of at least 4 HD, the bottle gains 1 charge.
The bottle is automatically restored to 4 charges
at sundown.