Played an RPOL game where one of the party was an energy master PRC.
It was cool because all of her attack spells were laced with the element she mastered.
IDK if it is a SRD or something from hall of heroes back in the day but I believe it works like:
1.) Pick an element to master
2.) Pick an element to be denied
spells cast do extra damage laced with the element they mastered.
Jane is an ice master, she forfeits fire.
She can't cast fire spells but when she casts magic missile her her missiles are covered with ice and do extra damage as ice.