max mp eater first. with it and heal , since heal can attack multiple undead monsters, you can get a pretty good chance of taking mp. it will seem like you will never run out of mp with max heal and max mp eater. YOu got a certain success rate but look, u will have a chance of 6 lupins to take it from them. You will be sure that the amount u take will be atleast half of the number no less.