I think making Aetherflow link with the summoned Egi would be a fun idea. Like when you summon the Egi, Fester and Painflare become ‘X-elemental’ with different effects and charges for each Egi.

Like Ifrit’s could be a melee range burst attack oGCD to use after Crimson Cyclone / Strike combo with just one charge and maybe a conal aoe for Painflare. Garuda’s could be lower potency oGCDs with four charges so you can weave one in after every Emerald Rite / Catastrophe. Maybe they could make it so every use of the oGCD shortens the cast time for Slipstream, meaning if all four are properly executed it has its cast time shortened to 1.5s or instant. Then Titan could have two charges since it already uses Astral Flow for oGCD as well, maybe it could get something more utility focused like a stun for aoe or damage debuff for Fester.

In terms of utility I still would really like to have more control over when I can use Everlasting Flight and Rekindle. I also wonder if it would be too OP for Physick to either scale from INT, or perhaps upgrade to Rekindle when you learn Summon Phoenix, but with a high Mp cost (1000?) and similar cast time as Physick to compensate for availability. I feel like Rekindle is distinct enough from Vercure that it would feel like a copy+paste, and since Summoners can’t Dualcast and don’t have infinite reserves of MP, it would even out in terms of balance (I think lol)