Elemental Exposure

Elemental Exposure is a  passive skill, unlocked at level 68.

In-game
Indirect damaging attacks (like Tal Rasha's Elements set s), and  attacks, or special attacks triggered by wargear, contribute to Elemental Exposure as well. For maximum effect, Wizard will need at least three skills with different damage types (provided the fourth is the Elemental Damage or damaging proc from weapon). For the single damage type builds, Elemental Exposure is, for obvious reasons, much less effective.

The amount of stacks is actually visible on the target: each affected enemy will be highlighted with up to four glowing orbs above their head, color of the orbs corresponding to the damage type.

Each type of damage applies as a separate debuff, and does not refresh the duration of others.

Elemental Exposure from different Wizards only stacks if they are using different damage types; that is, the total amount of stacks will not exceed four, and two identical stacks do not stack.

As of patch 2.4.2, damage amplification only affects the attacks of the casting Wizard, and not of other players.

Enhancements

 * Primordial Soul (Legendary Source): increases damage bonus to 10% per stack (40% total).