I summoned Odin a few battles ago, maybe 2 battles ago, and now I just entered a new battle but now the Summon option is grey, is there a limit to how many summons I can use? Or a certain time period I have to wait till I can summon him again? I love summoning Eidolon's there one of the coolest things in the battle system.
I've tried reading the "Primers: Battle - Eidolon Battles" in game but it says nothing about time periods or anything.
Edit: I just realised the little bar under my HP bar needs to be at 3 to summon, but how does it rise? Is it just everytime I attack?