Your choice of summon influences your team’s combat proficiencies in several ways. Each summon comes with two passive effects: the pre-summoning effect takes effect immediately, while the post-summoning effect kicks in as soon as your team successfully invokes the summon. Which summon to choose highly depends on the makeup of your team and your team’s playstyle. Some summons, like Shiva, Ifrit, Odin, and Alexander, have effects that every character can take advantage of, regardless of their HP Attack/EX Skill loadout. Other specialized summons, like Ramuh, Leviathan, and Bahamut, directly affect certain EX Skills, so some of their buffs may go to waste if your character isn’t equipped with specific skills. Generally, Shiva and Ramuh are strong picks. However, if you can coordinate with your teammates, you can go for a highly specialized loadout to take advantage of a summon’s buffs (such as gearing up all of your team with Enfeeble and choosing Leviathan as your summon).
Each summon has two types of normal field attacks and one signature finishing move. Upon summoning, they deliver three normal field attacks (chosen randomly between the two attacks). After the third field attack and before leaving the battlefield, the summon performs its signature finishing attack, potentially devastating the entire enemy team. Summon attacks cannot be guarded, so a common strategy is to exploit your summon’s field attacks by taking a hyper-aggressive approach as your foes scatter to avoid the summon’s powerful attacks. Additionally, summon attacks do not cause a Bravery break, giving you an opportunity to reap the Break Bonus on vulnerable targets. Note that each team can only summon once per match and while a summon is active on the battlefield, game time is halted.