BacMot is a legendary Runeword created by combining a Bac Rune of Ritual and a Mot Rune of Invocation.
How to Create BacMot
You can create BacMot by adding the legendary Bac Rune of Ritual and the rare Mot Rune of Invocation to a two-socketed Helm, Chest Armor, Pants, or Two-Handed Weapon.
Bac - Travel 5 meters. (50)
Mot - Gain a shadow from the Rogue's , reducing damage taken per shadow. (150)
Dark Shroud
Overflow
BacMot can not overflow because the amount of Offering you receive from the Bac Rune exactly fills the required Offering of the Mot Rune.
Overflow occurs when your Ritual generates more Offering than required for the Invocation. The overflow effect is proportional to the amount Offering overflows.