I wouldn't mind some how incorporating attacks themed around individual great worms. Maybe instead of deriving powers from them via eyes or otherwise we just get inspired by their movements. Like a circular aoe based on midgardsormrs spin attacks from o10n/s, a twister thrust like Bahamut, Vritra's breath attack, nidhoggs hot tail turned into elaborate soaring spear fired line aoe, I'm not sure what to add for tiamat but perhaps something like estiniens horrid roar when you use him against the proto weapon. She does have a roar to summon her kin from afar so instead of a damage rebuffed like horrid roar we can get a summoner style attack where every enemy hit gets swoopped on by a dragonet.