BP+Release Summoner is the most TP-feeding-efficient damage source if played well. BPs give 0 TP. This is another one of Summoner's strengths that you abandon when you melee something or let your avatar melee it.

Remember Scylla? Pretty nasty monster with the 75 cap. Uses several TP moves back to back when it gets TP and generally decimated whoever it was facing. Regardless, it was duo'able by RDM+SMN because it doesn't have regain and that combo can kill it without ever giving it TP.