BacMet is a legendary Runeword created by combining a Bac Rune of Ritual and a Met Rune of Invocation.
How to Create BacMet
You can create BacMet by adding the legendary Bac Rune of Ritual and the magic Met Rune of Invocation to a two-socketed Helm, Chest Armor, Pants, or Two-Handed Weapon.
Bac - Travel 5 meters. (50)
Met - You leave the Necromancer's Desecrated Ground behind you for 3 seconds, dealing damage to enemies within. (100)
Overflow
BacMet can not overflow because the amount of Offering you receive from the Bac Rune exactly fills the required Offering of the Met Rune.
Overflow occurs when your Ritual generates more Offering than required for the Invocation. The overflow effect is proportional to the amount Offering overflows.