NocXal is a rare Runeword created by combining a Noc Rune of Ritual and a Xal Rune of Invocation.
How to Create NocXal
You can create NocXal by adding the rare Noc Rune of Ritual and the rare Xal Rune of Invocation to a two-socketed Helm, Chest Armor, Pants, or Two-Handed Weapon.
Noc - Inflict a Crowd Control that isn't Slow or Chill. (10)
Xal - Gain 20% Maximum Life for 6 seconds. (200)
Overflow
NocXal can not overflow because the amount of Offering you receive from the Noc Rune exactly fills the required Offering of the Xal Rune.
Overflow occurs when your Ritual generates more Offering than required for the Invocation. The overflow effect is proportional to the amount Offering overflows.