Generally speaking, Final Fantasy’s summons are a step above most simple magic spells or attacks.
Tending to unleash the raw elemental strengths of fire, ice, lightning, and so forth, evoking them is usually costly on the MP bar but worth the output in the devastation that can be inflicted (on a full enemy party to boot).
On the other hand, though, there’s much more to being “powerful” than raw damage output alone. This quality, in fact, can be rather immaterial at times, when a physical attack and summon alike can both deal 9,999 damage, which has historically been the cap.
To be especially formidable, then, a summon needs to hit multiple times, or have a very strong effect beyond simple damage. Throughout the series, summons have provided a range of boons like this, and in a few cases, a lot of players aren’t even aware of that summon's potential. Here are the most powerful examples players have ever been blessed with, and exactly what makes them so effective.
10. Knights Of The Round: Final Fantasy VII
This mighty Materia, hidden in a cave that isn’t marked on the map and that is accessible only via gold chocobo, strikes the foe 13 times. What makes it truly devastating is the fact that it can be used alongside the Mime Materia, allowing the party member equipped with Mime to immediately repeat the attack again (with the proper timing). For Omnislash, Highwind, Catastrophe and other multi-hitting Limit Breaks to be Mimed, the correct character must be equipped with Mime.
Even without this advantage, there are few summons as iconic, or as damaging. There’s a reason why so many players remember spending hours breeding chocobos in order to acquire it.
This is the only possible way to unlock the Materia for use, aside from equipping the Master Summon Materia. Among the most valuable in the game, it allows the equipped character to use any summon monster unrestricted (typically, each can only be used a certain number of times in each battle).
The Master Summon Materia, however, requires the party to defeat Emerald Weapon, which is no mean feat without Knights of the Round in the first place.