The Infusion system, introduced in The Taken King, allows you to transfer the Light Level from a higher-Light piece of gear to a lower-Light piece of the same slot. This is crucial for maintaining your favorite weapons and armor while still increasing your overall Light Level. To infuse, select the item you want to upgrade, then choose the 'Infuse' option. You'll need a higher-Light item (the 'infusion fuel') and some Glimmer and Legendary Marks. The infused item will gain a significant portion, but not always 100%, of the Light from the fuel item. This system encourages you to keep powerful perk rolls on your gear and continuously upgrade them as you acquire higher-Light drops. Prioritize infusing your most used weapons and armor first.
