It's really simple, and I guess it could also go in any of the classes cases.
-coughcoughcough-
Say I have.. 2k health while I'm on Teli. A nearby monster has taken about 500 health away from me. I now have 1.5k health, I use a toxicology move, which I will refer to as Sap, on the target that has .. 2k health. My health goes up to 1.6k and his health drops to 1.7k, or something similar.
I plan that this could be used to a priest's, or any other class', advantage. Seeing that priests only have the option of healing or doing damage, maybe they could get the chance to do both. So if the target is at low health, but so is the caster, then the caster can heal themselves, not to mention rid of the enemy also.
The example isn't very specific, but I was thinking maybe it could drain enough to restore 4-6% health, or simply drain given percentage. I'm bad at statistics, I know. |D