Ideas for Overcasting?

[Fenrat]

In the name of heroic fantasy, I'd like to see rules for overcasting. To me, overcasting is casting a spell:
1) Beyond your daily allotment; or
2) A spell within your level to cast, but that you don't know; or
3) A spell normally beyond your normal level to cast.

I view overcasting as something that one does in very desperate situations .. something that could have dire consequences depending on what you are trying to do. Perhaps trying for an extra first level spell requires a DC check or you get a headache and can't cast spell for a bit ... but perhaps trying for an extra 9th level spell would be much more dangerous.

And overcasting could be tried more than once .... but each time the chance of serious harm (perhaps even burning one self out and permanently losing spells or even the entire ability to cast spells).

I would love to see something in the Pathfinder RPG on overcasting. However, I've never been able to come up with something that works....

Any input from all the great gaming minds on these boards?

[Kvantum]

Two points of Con burn (Cha burn for undead) per spell level "overcast", plus automatic exhaustion. If you really need a Wish or a Meteor Swarm, you can get it, but it'll cost you.

(Ability burn is like ability damage, but can only heal through time - magic won't help its loss.)

And 4 points of burn per spell level beyond your normal casting ability plus one per spell level that you can normally cast. Example - 11th level cleric wanting to cast resurrect? 10 (4+6) points of Con burn plus automatic exhaustion plus normal costs. 1st level wizard trying to cast Wish? 33 points of Con burn (8*4+1) plus automatic exhaustion plus normal costs. Hope that 1st level mage has a 34 Con... or else he can't cast it.

[Fenrat]

Not bad ... I will have to play around with that idea .... but what I've been trying to create is some sort of check they have to make .... with both an effect even if they do make it (bad headache, or worse with associated effects) ... and the possibility of worse if the DC is failed and real bad consequences if the DC is failed by a large amount.