Incarnum
A Dungeons and Dragons 3.5e magic system that earned the title of "Most Confusing System Ever."
OK, so this is how it works: you have a bunch of mystical energy constructs called Soulmelds that sit where your magic items go, except you can't have more than one per item slot (which they call Chakras) unless you take a feat and they don't stop you wearing magic items most of the time.
You then have two non-exclusive ways of charging these up: you can put points of magic gunk called Essentia in them to increase stuff like DCs and bonuses, or you can bind them to a chakra (sometimes you can choose from a bunch of chakras for one soulmeld, unless you're a Totemist which has a special chakra that isn't actually a body part that turns the energy thing into a monster body part like claws OR you're high enough level to get the feats or class features that let you bind soulmelds to your heart or soul chakra), which does stop you wearing a magic item, but it becomes about as strong as a magic item.