Clara is OBVIOUSLY the most IMBALANCED & OVERPOWERED GOD TIER esper in this game, so much that 2nd best esper is not even close to her level. 

She single-handedly breaks the balance of the entire game, here's why:

1. Her passive is the main problem. She has PURIFY, IMMUNITY, and convert HP to SHIELD. This can be easily a skill with CD on any other espers, yet on her, it's casting EVERY TURN without CD.
2. Her 3rd skill compared to UNAS, a SHIMMER LEGENDARY ESPER (which is about 14 times more rare than Clara), they both have AP Boost (30% on unas vs 20% on clara) but Unas does nothing (let's be honest, the dmg is next to nothing) yet Clara has a 30% Hp teamwide heal. Would you trade 10% of ap boost for 30% teamwide heal (which converts to shield btw)? Isit even fair? Let that sink in.
3. She has the highest base speed in the game. She, a HEALER SUPPORT, has the speed of 106 which doesnt make any sense! Any other healers in the game doesnt even come close! (Sally 96, Ahmed 94, Cecilia 95) Again, taking Unas for comparison, he IS a support with speed scaling in his skills, so him having the highest base speed in game makes total sense, but CLARA ?!?!?! The speed alone is already not justified, not to mentioned the purifies + healing + immunity that procs EVERY TURN WITHOUT CD. She's a complete domination in this game.

I've recently just pulled Clara and she magically made all the difficult stage so much easier, WHICH IS TOTALLY NOT OK for one single esper to do so much!

Imagine players without Clara, there is no replacement. You will need Gab + Hengyue + Unas to fill her shoes. ONE SINGLE ESPER can play the roles of 3 espers, think about that.

Oh, we haven't touched on PVP.

Put her in Speed cleave team, OP.

Put her in Def Donar/Rensi team, OP.

Put her in any team and she literally makes the whole team OP.

Just take a look at Tier 12 above point war teams, it's rare to find any team without Clara in it. Why is that? Because she OVERPOWEREEEDDDDD AND NEED TO BE NERFED.

#dontletclararuinsdislyte