This is personal opinion and I will only be speaking for the 99% of SCH / WHM / AST.
additionally this is just based on having perfect OGCD and GCD planning while dps and possible into the future of ultimates.

Using FFlogs metric

current standings @ 99% healing

healing scores AST 109, WHM 105 , SCH 96 - Since the buffs when played properly AST is actually a healing powerhouse without actually clipping much into its healing resource however it still has its nocturnal sect issues

healer DPS - which a good metric since that means they are only OGCD healing and

WHM 8,224
SCH 8,104
AST 7,774
Average across all 4 fights, HOWEVER this is skewed because of E1s so lets look at per turn

E1s


E2s


E3s


E4s


Feedback suggestion
As you can see all the healers are close WHM is still very ahead but brings less utility, however for the amount of work and planning AST puts out it should be rewarded quite higher at 99 but not to the point it becomes super meta because it is unhealthy for the game it is a hard spot to balance this type of job. my suggestion is

Malefic changes
change cast to 1 sec (maybe to help with the abundance of clipping), 250 potency or 260

OR

Card Changes
all cards now give 1% more. and malefic remains the same.


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Side suggestions that are just I wish and less about actual balance and more about thematic

Celestial Intersection in diurnal I wish was 15sec and in nocturnal an aoe regen with 60sec cooldown, however I do not know how difficult that would be hard to code but it would solve a lot of weird ticking issues with nocturnal/diurnal.