This is a concept for a Sage rework to make it not an 80% clone of Scholar and actually fulfill the identity Sage was described as having by Yoshi P in lead up to Endwalker's release. I've shared over on healer threads that I've gradually fallen more in love with. Here's the breakdown:

Name: Sage (Reworked)
Role: Healer
Identity: Crit Healer

Gameplay: There are three major component changes to how Sage works in this concept. First is Addersting. Addersting is now generated each time you score a critical hit with your GCD spells; each cast of a spell can generate 1 Addersting for any damage that crits from offensive spells (so only 1 per AoE even if you crit on multiple enemies) and 1 Addersting for any healing that crits from either healing spells or Kardia healing. If an attack spell both crits from the damage it deals and crits on the Kardia healing, you get 2 Addersting for that spellcast. Second is Toxikon, which is now an OGCD attak with the same potency as your Dosis spells; it has a short 10 second cooldown with 2 charges, and is your main spender of Addersting--your reward for scoring critical hits. Third are Eukrasia and Dyskrasia. Attack spells no longer heal your Kardia partner automatically; instead, using Eukrasia augments your spells to have different healing effects. Dyskrasia, on the other hand, is changed to be the opposite of Eukrasia and is used to make your spells more dangerous. Both cost 800 MP to use and will play a part in creating a system of proper MP management in this Sage's kit. Example:

Dosis: Your standard single target GCD. Costs no MP.
Eukrasian Dosis: A slightly weaker attack with AoE falloff that additionally heals your Kardia partner. Does not have its own MP cost, but will cost 800 MP by proxy of requiring Eukrasia.
Dyskrasian Dosis: Consumes 1, 2, or 3 Addersting (based on how many are available), to inflict a debuff on your target that increases the rate at which your spells score critical hits, a rate of 5%, 10%, or 15% based on the Addersting spent on Dyskrasian Dosis. This effect lasts 30 seconds.

Your standard AoE spell has been renamed to Paroxysm since Dyskrasia was used to be more thematically appropriate and follows a similar pattern to Dosis from above. It's Eukrasian variation now provides AoE healing around your Kardia partner, and it's Dyskrasian variation is the same as Dosis but for AoE in exchange for a higher MP cost. There are other offensive spells as well that have Eukrasian and Dyskrasian effects.

Addersgall also changes to some degree. You still generate 1 every 20 seconds, but you no longer spend them on direct healing abilities. Instead you spend them on different tools that help support your engagement with Kardia rather than obscenely accessible and powerful heals that replace it. Zoe is now an Addersgall spender that guarentees both the damage and healing of your next spell will score a critical hit. Soteria also spends Addersgall and gives you a "Soterion Target" who also receives your Kardia effects for a set duration. And Krasis lets' you burn Addersgall to restore your MP.

I have more details over on the healer suggestions megathread, but I've been playing around with it more since then.