I'm about to start running a Fate Core game that focuses on magic-using PCs. As I've conceptualized magic in the setting, it's easy to use but very dangerous unless one has invested a lot in the associated skill. I've been kicking around a few notions, but I'm curious what kinds of mechanics, either in published systems or in your own system hacks, have been used to capture the notion of an inherently risky flavor of magic.
In particular I'm looking for mechanics that dish out stress, consequences, or possibly wider reaching aspects when things go wrong. I've read the Fate Toolkit, and the Voidcallers device of "Doom Points" is one good example, but I haven't run across others.
Edit: Some examples of what I mean by "risk".
I do not have in mind social consequences of being a magic user or any thing which might lead to compels just from having magical ability. Nor do I have in mind "mundane" accidents of the kind you could make with a weapon (like hitting the wrong target). Mere unreliability (you try to throw lightning but it unexpectedly fizzles) also isn't what I have in mind.
I do have in mind effects that follow from the use of the magic as such; that is, non-mundane effects that could be avoided by solving the problem with some other skill set. This could include, but is not limited to: unusual alterations to one's physiology; your fireball spell is more like a flamethrower spell and you can't turn it off; the use of said fireball spell taints the area for years to come, causing things to periodically spontaneously combust; etc. Succeeding at magic, but failing to manage the risks, should leave the character only slightly better off than letting the bad guys win; and if you fail and also take the side effects, you should be worse off than if you had just let the bad guys win.
I would think of Lovecraftian magic as the extreme end of "risky magic", where using magic at all will probably inevitably destroy you in some unusual way, but it needn't be quite this bad.