Cast a magical poisonous arrow that does X-Y poison damage.
Poisoned deals X-Y poison damage per turn.
A direct damage and status chance upgrade to Magical Poison Dart, as with 12 or more Intelligence the cooldowns are equal. Note, this spell book can be found near the entrance to the Light House in Cyseal. It is not sold at the vendor so consider this when you respec your character at the Halls of Darkness.