[Plasmabunny]

Well, you could just ignore the Malus rule, or apply it only to spells that could be abused. Or if you want a better ingame explanation, it could only apply to healing spells (makes sense that using your own life force to fuel a spell might make it harder to control if you plan to use it to boost someone else's life force). Malus could be your life energy rebelling against the use.