AhuTun is a legendary Runeword created by combining a Ahu Rune of Ritual and a Tun Rune of Invocation.
How to Create AhuTun
You can create AhuTun by adding the legendary Ahu Rune of Ritual and the magic Tun Rune of Invocation to a two-socketed Helm, Chest Armor, Pants, or Two-Handed Weapon.
Ahu - Lucky Hit: Up to a [100|%|] chance against Injured enemies. (10)
Tun - Invoke the Rogue's Stun Grenades, Stunning and dealing damage to enemies. (100)
Overflow
AhuTun can not overflow because the amount of Offering you receive from the Ahu Rune exactly fills the required Offering of the Tun Rune.
Overflow occurs when your Ritual generates more Offering than required for the Invocation. The overflow effect is proportional to the amount Offering overflows.