Two notes:
One: "Stop complaining, I didn't make it as powerful as I could have" is never a valid argument. Just getting that out of the way.
Two: Considering she has 360 MP(and the tier one perk boosts it from 240 to 360, so ahem no), and uses MP to improve all of her other stats, we both know 'it's not as powerful as it could be' is bullshit, as demonstrated quite nicely by the 500% stat increase. She could do 250% boosts and one-shot everyone, one at a time. With the triple attack perk (going from 160% potential damage to 240% is a 'small' upgrade?), she could do 300% increase and take out 3 people. Obviously, you aren't abusing this. I'm pointing out the power of Mana when you use it to simply boost yourself and there is not limit on the max you can do this. It becomes extremely potent, because it becomes multiplicative(side note: Mana is one of the only stats that scales rather linearly, if you can actually make use of it, rather than, say, Resistance, or Defense, which are currently useless in minmaxing terms; better to just pump up Health(Magic, on the other hand, scales exponentially, of course...>.>...if you have the Mana for it, that is.))
Three: This really shouldn't be a separate thing but I figured I'd do three, and besides, I have to bring it up. A single counter attack at full damage is a tier 2 perk, properly, based on what everyone else has as their perks. Using the highest power level in a given set as the base from which to scale off of is how Power Creep occurs, rather than a nice variation of people having different advantages in Power. Look at it in DotA terms. Not everyone's Q ability is amazing. Some heroes Q ability is amazing. But if you're designing a hero for whatever reason, saying (and I'm grabbing names at random so bear with my meagre knowledge of DotA(I played LoL so I know the basics)) "Well Bloodseeker has this ability, so I can do something similarly powerful...and Nature's Prophet has this other one...oh and Enchantress has this..." is not actually going to create anything resembling (*shudders*) balance. Some heroes have abilities that are essentially flat upgrades of what other heroes have, yes? This is balanced out by weaker other abilities(or not balanced out at all as I know they don't actually have all that great balance from what I've heard), and the like. So when you're making new ones, you base things off the mean or the median. If you adjust one thing up, you gotta adjust another down. You don't base them off the top. Unless, like me, you aren't designing for balance, and you have a very specific goal in mind when you make things like this...
Rambling half-rant over.