The Venom Staff is a Hard Mode magic weapon. It is very similar in style to the Poison Staff, except Venom Staff shoots four to seven poison fangs in the direction of use, rather than just one to four.
The Venom Staff inflicts the Venom debuff on enemies.
Venom Staff Terraria 1.2.3 Strong Magic Weapon
Notes
Like with most magical weapons, the best possible prefix for the Venom Staff is Mythical.