i dont think this can be done since its a new skill all in itself lol
To make it fair and somewhat useful in Mass PK, maybe make the AOE buff cooldown 5 minutes long and reduce the damage reduction when attacked from 30% to 15%-20% instead?
Falling Petals doesn't reduce received damage, what the heck?Also, your suggestion by making it 5min cooldown would be actually a huge nerf for this skill.
-1 Mystics already have Conforting Mist & Gaia`s Blessing and that makes 1 more than the ep has. Another aoe heal would make the class even more op and they were never intended to be a full support class.
Falling petals is already one of the 3 useful Mystic heals that we have that is spammable.