PocTun is a rare Runeword created by combining a Poc Rune of Ritual and a Tun Rune of Invocation.
How to Create PocTun
You can create PocTun by adding the rare Poc Rune of Ritual and the magic Tun Rune of Invocation to a two-socketed Helm, Chest Armor, Pants, or Two-Handed Weapon.
Poc - Spend 5% of your Maximum Resource. (5)
Tun - Invoke the Rogue's Stun Grenades, Stunning and dealing damage to enemies. (100)
Overflow
PocTun can not overflow because the amount of Offering you receive from the Poc 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.