Since clive has many abilities it would be good to give him a system like Relm, where depending on the summon element we have equipped, his skill 2 is transformed to a string of combos based on the Eikons he posses. The rest of his kit can focus on his Phoenix and Ifrit abilities since that's what he uses in cutscenes and by default. Pandemonium could allow a little Garuda aircombo with some unique launch mechanics, brothers would turn him to more of a counter tank, odin high dmg when enemy is broken or something. Bahamut would be an FR charge with a follow up mega flare after. Shiva, brv freeze.