AhuEom is a legendary Runeword created by combining a Ahu Rune of Ritual and a Eom Rune of Invocation.
How to Create AhuEom
You can create AhuEom by adding the legendary Ahu Rune of Ritual and the legendary Eom Rune of Invocation to a two-socketed 
Helm, 
Chest Armor, 
Pants, or 
Two-Handed Weapon.
Overflow
AhuEom can not overflow because the amount of Offering you receive from the Ahu Rune exactly fills the required Offering of the Eom Rune.
Overflow occurs when your Ritual generates more Offering than required for the Invocation. The overflow effect is proportional to the amount Offering overflows.
Legions
Helltide