Gives both secondary and primary weapon ability for chance to burn enemies. It is best used in combination with weapons with high fire rate to increase chances for fire to apply (or that already have a chance to ignite enemies to further increase the chances of igniting the enemy), and weapons that already have elemental abilities, e.g. Sub Zero. It also decreases damage dealt to enemies by 20%.
- It has been renamed as "Ignition Rounds" in version 20.8, because "Phosphorous" had too many letters and wasn't displayed properly.