This script allows you to set a range of percentages that could be randomly selected by the system at the beginning of the party selection stage.
That percentage will be speedily applied to the actual Skill's Cost ONLY IF either the actor or the enemy trooper contracts a disease, what this script calls the COST_STATE.
As long as that specific state remains, the hero or trooper will not spend the normal amount of SP unless they get really lucky or the effects of the state finally wear off.