Great Weapon Fighting

Source: System Reference Document 5.0
The text on this page is Open Game Content, and is licensed for public use under the terms of the Open Game License v1.0a.

When you roll a 1 or 2 on a damage die for an attack you make with a melee weapon that you are wielding with two hands, you can reroll the die and must use the new roll, even if the new roll is a 1 or a 2. The weapon must have the two-handed or versatile property for you to gain this benefit.