Crossbow, Alchemal (3.5e Equipment)
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This looks to be a normal crossbow, but on closer inspection, you see 2 switches that when one triggered opens up a hidden compartment meant for a vial or other alchemical substance, the other applies the contents of the vial to the loaded bolt.
This crossbow can store a vial of poison or other alchemal substance (Alchemist Fire, Holy Water, etc.) in a hidden compartment that can be applied to the currently loaded bolt so when fired, the bolt gains some of the properties.
If the substance deals damage (such as acid or alchemist's fire) the bolt deals (in addition to normal damage) the damage normally dealt by the substance with no splash. If the substance does not deal damage (for example tanglefoot bags and holy water) then the bolt does their effect in addition to it's normal damage without any splash. Poisons are applied to the bolt as is normal.
Reloading the compartment is a move action that provokes AoO's, and applying the substance is a free action. This also can be put into any crossbow, just add 30gp to the price.
Each alchemical substance can be applied to five bolts before being depleted, vials of poison can only apply to three bolts before being depleted.