Bow of the Viper
The fang of a venomous snake that has wounded at least one humanoid.
Both limbs of this bow are scaled and end in a snake’s open mouth.
You gain a +1 to attack and damage rolls while wielding this weapon. As a bonus action, you can expend 1 charge to poison one arrow suitable for the bow for 1 minute or until it is used to damage a creature When a creature is damaged by the blade’s poison, it makes a DC 15 Constitution saving throw or takes 1d10 poison damage and becomes poisoned for 1 minute.
Alternatively, you can use an action to expend 2 charges to cast the following: protection from poison , shillelagh (transforming the bow into a snake-headed 1 quarterstaff ), thorn whip (causing one of the bow’s snake heads to lash out).
The bow of the viper has 4 charges and regains 1d4 expended charges each dawn. If you expend the last charge, roll a d20. On a or 5 or less, it can no longer regain charges and becomes a 1 longbow .