Halo of Thorns
Artificer Attack 1
You enchant your ammunition with poisoning magic, then transfer that enchantment onto one of your allies close to the target.
Ranged weapon
Target: One creature
Attack: Intelligence vs. AC
Hit: 2[W] + Intelligence modifier poison damage, and choose one ally within 5 squares of the target. Until the end of your next turn, any creature that hits that ally with a melee attack takes poison damage equal to your Wisdom modifier.