Each individual foe, ally, and weapon is associated with one of six elements. The elements are Fire, Water, Earth, Wind, Light, and Dark.
There are six elements, divided into two superiority wheels.
In the tetra-element wheel (sometimes colloquially referred to as the "main elements"), every element has a strength and weakness:
- Fire is strong against Wind and weak against Water
- Wind is strong against Earth and weak against Fire
- Earth is strong against Water and weak against Wind
- Water is strong against Fire and weak against Earth
In the sub-element wheel, elemental superiority always goes to the player:
- Light is strong against Dark
- Dark is strong against Light
Fighting with the superior element is called being "on-element" and comes with many benefits:
- Damage taken is reduced by 25%
- Attacks gain a 50% elemental multiplier
- Higher chance to successfully inflict debuffs
- Party members have a chance of dealing critical damage (if they have any sources giving them a chance to crit at all)
When the enemy has the superior element, you are similarly disadvantaged:
- Damage taken is increased by 50%
- Attacks get a -25% elemental multiplier
- Lower chance to inflict debuffs
In some fights, such as Unite and Fight Nightmare-difficulty battles, you are not affected by off-element resistance. But generally, when fighting against an enemy that is the same element as you are, your chances of inflicting debuffs on it are even lower than if the enemy had the superior element.
Certain enemies (e.g. Primarchs) will take less damage from all elements that are not superior to theirs.
Multi-elemental foes (also colloquially called "non-elemental" or "null") have no elemental weaknesses or strengths.
There is no elemental damage bonus from attacking a multi-elemental foe with Fire, Water, Earth, Wind, Light, or Dark elemental attacks. When multi-elemental foes attack, they will deal either Fire, Water, Earth, Wind, Light, or Dark elemental damage.