Almost all of them? Any 40%+ event Eidolon is better (Elemental and character), because keep in mind, 1-star Fafnir has AWFUL stats still. Why would you use a 1-Star 45% Elem 1297 Atk Fafnir if you have a MLB 45% Elem 2048 Atk Adra? Even Reiki with her awful 1530 Atk is better.
summon effect?