UrTec is a magic Runeword created by combining a Ur Rune of Ritual and a Tec Rune of Invocation.
How to Create UrTec
You can create UrTec by adding the magic Ur Rune of Ritual and the magic Tec Rune of Invocation to a two-socketed Helm, Chest Armor, Pants, or Two-Handed Weapon.
Ur - Your Minion or Companion kills an enemy or dies. (10)
Tec - Invoke the Barbarian's Earthquake, dealing damage to enemies within. (100)
Overflow
UrTec can not overflow because the amount of Offering you receive from the Ur Rune exactly fills the required Offering of the Tec Rune.
Overflow occurs when your Ritual generates more Offering than required for the Invocation. The overflow effect is proportional to the amount Offering overflows.