Some people get hit harder then others when they do some physical tasks. Maybe that would carry over to magic as well?
Bonus: 5 karma per level (1-3 levels)
Requirement: magician or aspected mage
You can run a mile in under 7 minutes, you can bench press 200 and not break a sweat, but when you cast a single spell it hits you like a ton a bricks. Increase the drain value for every spell you cast by the number of levels you have in this quality. This does not change the type of drain from stun to physical.