Looking at zoey, I think every mystics (and healers) should have 'on spawn skill' specific to their classes.
Mind warder : increase cooldown of all enemies by 1 turn
(Because all other classes don't need earlier cooldown! So all Shadows should prolly get on spawn stealth and on spawn swap

)
Rune Magus : 15% def buff to all allies based on mag for 2 turns
(A bonus persistent for 2 turns wow, which cleans resilience)
Elementalist : Cast tile burn damage by 35% of mag to all enemies for 2 turns
(WOW this helps to clean resilience too!)
Warlock : Cast poison damage by 25% of mag to all enemies for 3 turns
(Sweet, let's add bleed too)
Archbishop : Heal all allies by 20% of mag for 3 turns
(Nice, now let's get rid of that resilience. Double heal from turn 1! Heal trigger anyone?)
Inquisitor : Reduce incoming damage received by all allies by 15% for 2 turns
(This is probably the only one that looks ok)
Spiritwalker : Reduce cooldown of others in aura by 1 turn
(Oh this is not too bad also)
Witch Doctor : Poison enemies by 20% of mag for 3 turns and leech 100% of damage to heal all allies
(So nobody dies for 3 turns woohoo! BUT WHY U MAKE WD MORE OP THAN WARLOCK. SO UNBALANCED. MAKE MYSTICS GREAT AGAIN)
Why? To counter resilience because guardians are already OP with 30% swap/knockback resist and you can always use another resilience rune to resist it. As for healers, they can finally support/heal the team from turn 1.
(Yeah man natural 30% resist yknow!)
(And yeah man all my persistent healers are trash)
Anyway, it's almost 2 months from when this thread started, developers should at least have an idea about how to work on mystics and healers... Don't let us down

I really hope the devs don't follow your ideas.
Bruh, do you even calculate?
First of all, of course not all class will cleanse resilience, if all skill cleanse resilience there won't be any diversity on classes.
I don't get what you mean on the Mind Warder part so I'll just skip. if only you write like a normal human being and not in sarcasm maybe I can understand.
Rune Magus' 15% def only last 2 turns which will only be good against rangers, by the time skills are not on cooldown, the buff is already gone. This buff will also be decent on PvE.
Elementalist's will bypass resilience, which renders resilience useless, but not for normal skill. Resilience would still help but will not be as powerful as before.
Bleed? What does it have to do with poison? Am I thinking too far? Or are you thinking too far?
Heal trigger might be a problem, but do you actually see anyone with a decent heal trigger team owning arena? healers don't have base high atk anyway, and in order to have high atk you would need to spend investment on her/him. Just like... I don't know... Rangers?
Okay, let's calculate rather than objecting other's ideas with unhelpful statements. Let's say a witch doctor has 10.000 mag. 20% of it is only 2000 which if you decrease with 1000 mag (and also def reduction) it's only 1000 damage. You must remember that healing is halved in arena so it's only 500 healing. Which part of it is actually more OP than warlock ? I wonder.
Now do you see any Taegen in everglades top players? I can only see one. While Zoey is different because she is valiant's evil counterpart. Then again you can make crit debuff and poison/tile damage as one instance of skill so it will only remove one layer of resilience.
Every hero needs a talent to maximize their potential. And the matchmaking In arena will match you with people with similar talent investments (survival of the fittest). But let's calculate the final result, guardians > mystics, because of the talent resistance, Guardians can own the tile easily with this talent. While mystics need to wait to cast a skill every 6 turns. I actually calculate rather than making assumptions.
These buffs also make mystic and healer slightly better in PvE imo.
I've given my ideas throughout the past 2 months.
Do you actually give any idea how to improve the game? I can only see sarcasm.