Looks like thats a hard-coded effect. If you want to change it you will have to use the script calls that alter Source Points for a character. CharacterAddSourcePoints and CharacterGetSourcePoints. You will also want to put a CanGiveSP check in the TargetConditions field so the skill can't be used on targets without SP.
Last edited by Sinistralis; 10/11/17 01:52 AM.