I know you’re not yet at the stage of development where you are overly concerned about balance, but I thought I might add some thoughts about the Mana Meteor ability.
As is, it allows meteors to be spammed infinitely. You don’t get any damage increase from having mana if you do this, because you only have whatever you generated in the cast time, but you can have meteors rain from the sky for full base damage as much as you want.
To be balanced mana meteor needs to have one or more of the following:
A short cooldown
A minimum mana cost
Reduced damage at very low mana (If damage is reduced at very low mana, make sure it reduces the damage from shrapnel as well)
While I find it very fun to fill the map with meteors, this doesn’t seem to be the intention of this particular ability. I imagine it’s supposed to incentivize you to cast at full/near full mana for triple damage, but when I can cast it a dozen times for normal damage instead, it seems to negate the core idea of that particular specialization.