Elemental Mastery

Elemental Mastery
This weapon is imbued with the energy of elemental mastery. Where the forces of the elements converge in harmony, each is equally potent. When used, this weapon has a chance of doing an extra 1d6 of any or all of the following elemental damage types : acid, electric, fire and cold.
 * 80% Chance of 1d6-4d6 extra elemental damage (Strom Lords website)
 * On-Hit chance to add 1d6 Acid, Cold, Electric, and/or Fire. Appears to be 10-20% for each to trigger, and 80%+ chance for at least one per hit. (DDOwiki contributor)

Elemental Mastery Guard
This item is imbued with the energy of elemental mastery. Where the forces of the elements converge in harmony, each is equally potent. When the wearer of this item is successfully attacked in melee, there is a chance that the attacker will take 1d6 of any or all of the following elemental damage types: acid, electric, fire and cold.