Guys... where is this sudden munchkining coming from?
I really did not expect to wake up to this, even when I like some of those ideas quite a lot.
First of all, we need to get our stuff to work before we can decide what to prioritise.
Secondly, why do some people think we should throw our Plasma Sphere right in front of us? No clothes will be damaged if we use it as intended.
Thirdly, I have to advise everyone that focussing everything we have on only one or two aspects of our character can be detrimental. All it takes for us to get utterly wrecked is an opponent that can use what we do good against us.
The only currently useless thing we have is Ice Sphere. I am confused why we even have it, considering that it does not really do anything and is not worth the effort.
-Infinity Edge is our weapon; still weak but can be buffed and has no additional limit on the number of attacks we dish out in our turn; once we have... about four attacks per turn, the weapon will really start to shine. Also grows some more with Reinforcement, seeing that it increases our Base Damage by 5% per Level; 30% extra at this point is not much, but that can become much more pretty soon.
-Plasma Sphere is our high damage option, which we only use against things that would not die from anything else because it also destroys our surroundings and sets them on fire; we do not always have the chance to crank up Alpha & Omega.
-Thermal Spear is our ranged option, which we use while engaging or to kite enemies around; Freeze also allows us to have some amount of crowd control because enemies get immobilised upon being hit
-Push does no real damage and never will; what it does is keeping dangerous things away from us and those fighting by our side. This is important when we go to the field with allies
-Iginition Aura is our core Ability; it deals damage all around and reduces damage we take. Granted, Plasma Sphere does all it does and better, but the aura will become superior again with time. It also comes with the added benefit of not setting Cerys' clothes on fire when she uses it against opponents swarming around her.
-Alpha and Omega is the end and also our Screw You against spellcasters once we bought the Item. We use this against opponents that nothing else can kill and hope we live long enough for it to work; the perfect Ability to take down a tank
To sum up, Plasma Sphere and A&O are our main options against Bosses while Thermal Spear, Ignition Aura and Infinity Edge will take down the regular enemies and small fry. Push and Thermal Spear are our crowd control.
Our main utility options are Thermal Control (which is already used plenty) and Flight; greater mobility is pretty useful... and we need to check if we can get Boosted Flight, which is basically being able to accelerate and decelerate at will, as well as changing direction without having to slow down and speed up first
Otherwise, we have Armoured Soul, Plate Armour and Regeneration... and I can see the probelm already.
Cerys is no tank. She is not supposed to be, which this shows very well: our Health and Resilience modifiers are separate and have to be leveled separately; this takes twice as much time as an actual tank should have, whose modifiers will be unified in one Ability. Our healing factor would need training as well for this to be viable, so it really is not.
If anything, taking a level here and there when we have our damage further up should be fine... but tanking this can never be our main means of action. We are supposed to have a tank standing in front of us anyway, so please keep that in mind.
I understand the people who ran the numbers and found whichever is optimal, but there is more one has to think about than what does the most damage. Plasma Sphere's Detonate is very likely to become Collateral Damage or even Apocalypse in due time... which means that it will destroy even larger areas when cast. We can not use it on everything and hope to get away with it.
Additionally, there is no "short term". Rukia already stated that we will be playing over years, so we should prepare to play the long game instead.
tl,dr: we need everything... except that weird Ice Sphere. It is a good balance that we should seek, not specialisation in one or two of our options.