[Autumn]

I wonder if Avalon having a From The Ashes once per battle style effect would make it good enough (or too good).

That depends on how much HP it recovers, so long as it gives badly beaten similar to how From the Ashes does still, it could work.

Recovering someone's HP based from FAI would work, or to about 25% would also work similarly, as to not overshadow From The Ashes' current effect.