After that attack, Chiaki glances around to see who got hit, who didn't, and who's still in need of healing. She's going to have to strike a balance between offense and healing in this fight - she needs to contribute to the damage as much as possible, but everything is lost if enough Heroes go down. In the end, she decides to cast Curaga on Nanami before turning toward Calamity Bahamut and firing off a Firaga spell.