Hay all, how about a negative quality in Shadowrun 5e?

Spell Sickness

Bonus: 15 karma

Your body rejects magic the way some people reject soy.  When you cast a spell, you become sick and take a -1 dice pool modifier to all actions until you do not cast a spell for two rounds.  If you cast another spell while you are sick, your dice pool modifier increases by another -1 that is cumulative.

What do you think gang?