Enkindle. Enkindle is much like Egi-Assault in that it commands your pet to use a special ability, which changes depending on which is summoned. It can only be used once every 2 minutes however, so it's best used when under the effect of as many party buffs as possible to make the most of its high damage.

Which EGI should I use?

When dealing with single enemies, the Ifrit-Egi is best. Most players use Ifrit as their default summon. It deals the most damage, but only to single targets. Ifrit is best for trials, certain raid battles, and most boss battles in dungeons.

How do you use Demi-Bahamut?

In order for Demi-Bahamut to use its actions, the Summoner must cast spells or command it to do so with Enkindle Bahamut. Deals unaspected damage with a potency of 150. Deals unaspected damage to target and all enemies nearby it with a potency of 650 for the first enemy, and 50% less for all remaining enemies.