Enchant Crossbow Bolts (Emerald) requires a Magic level of 27. It imbues 10 Emerald bolts each cast and turns them into Emerald bolts (e), which gives the effect magical poison. Each bolt has a small chance of poisoning your target for 5 damage initially. This is an alternative way of poisoning your enemies if you don't have a poisoning weapon in your inventory. It's also a great way to poison them from a distance. It is sometimes used in pvp to poison another player before switching to a different weapon or better bolts.