I had an idea for adding more summons to our roster.
We get an additional 3 on the same timer and available at any time. They do a big AOE with damage and an additional effect (sometimes supportive). All the animations are already there. Perhaps they take a little time to cast. We don't need gemshine attacks, but maybe we get a personal buff to damage.
Fenrir - Ice damage with paralysis or heavy
Leviathan - Water damage with dropsy
Susano - Lightning damage with vuln
Moogle - light damage and party esuna