The choices listed here are by no means the only ones available. Feel free to try out whatever combination suits your fancy. By making pacts with the the legendary "Avatars," these heretic mages have unlocked the secrets to the forbidden magic of Vana'diel. Summoners are great because they can do quests to get powerful Avatars, which in turn allow them to use their power to buff parties in great ways. Most summoners sub WHM or BLM to become even more useful.