I caught the wind for making classical OSE spells into dark and disturbing summonings in style of Voidcallers from Fate. Since it is rather small project I think it may be easier to accomplish than the heartbreaker.
You can find it in Fate SRD, in Fate System Toolkit -> Magic -> Systems -> Voidcallers. Let me give you an example:
Glow Tattoo (replace Light spell) - you summon a simple small tattoo on your body. Once per day per tattoo you can make part of your body glow like a torch for an hour. After that new line will appear somewhere on your body. Five new lines will create another tattoo and would allow another use per day. If you are willing someone who touches one of your tattoos may take it - it will wander somewhere on their body. If you don't use tattoo's power your vision will get slightly worse.
Each tattoo makes shadows around a little darker. It may not be that visible with one, but a few of them in one place will make shadows pitch black. That supernatural darkness may allow other horrors to slip into this world.