The wording of the spell is very open and by RAW it doesn't even seem like you have to be present for, or even on the same plane as, the damage being delt.
So does this mean if I somehow had 100 captive people on my person and then dealt each of them 10 points of damage in one round I would recieve a +100 luck bonus on the following round?
Could I theoretically set up a system where my X number of "captives" are kept somewhere safe while I go out adventuring. Every round have a spell/effect deal 10 points of damage precisely to each of them and then have a second spell/effect heal them for exactly 10 points of damage. Thusly giving myself a continuous +X luck bonus to my attack, saves, and skill checks anytime I pop Sadism?