An enhancement bonus is a type of bonus found on magic equipment. A magic weapon or implement adds its enhancement bonus to attack rolls and damage rolls for powers that have the weapon or implement keyword, respectively. Magic armor adds its enhancement bonus to AC.
- For example, a +3 longsword adds a +3 enhancement bonus to attack rolls and damage rolls of weapon keyword attacks it is used for, in addition to the normal properties of a longsword, such as its +3 proficiency bonus to attack rolls.
- A +4 magic wand adds a +4 enhancement bonus to attack rolls and damage rolls of implement keyword attacks it is used for.
- +4 dwarven scale armor adds a +4 enhancement bonus to AC while worn, in addition to the normal properties of scale armor, such as its +7 armor bonus to AC.
A character must have the corresponding implement proficiency to benefit from an implement's enhancement bonus. Enhancement bonuses on armor or weapons do not require proficiency, but the normal penalties for lacking proficiency apply.
The enhancement bonus on a magical weapon can also affect critical hits. Many magical weapons will say something similar to:
Critical: +1d12 per plus
Other magical item properties can refer to the item's enhancement bonus. For example, dwarven armor says "Gain an item bonus to Endurance checks equal to the armor’s enhancement bonus". Thus, +6 dwarven scale armor adds a +6 enhancement bonus to AC as well as a +6 item bonus to Endurance checks.