Another mark against the poor design of Destruction as a kill skill: Enemies.
I am at Adept level difficulty. That means 1:1 enemy:player damage.
I go up against a bandit mage. He's got fireballs.
I'm at 180 health when full. He double-barrels me with two fireballs and lops off 120 health.
That means more fireball damage than I can currently deal out myself.
I decide to do more testing and activate Godmode. I do a console check on his magicka level. 268.... an absurdly high level, I'd have to be at a far higher level than I am now to get that much.
He then Dual casts the fireball at me. What's his magicka now?
265.

That's the most infuriating thing about it. Mooks basically get superior spells that they can cast effectively for free.
WTH, Beth? Why do the mooks get the good Destruction spells while the player gets the awful ones that drain the magicka bar just trying to kill one foe? Why must we commit enchanting/alchemy abuse to get any sort of use out of Destruction while the melee and archery kill skills can stand on their own? Why do they get huge pools of magicka and sip magicka while spellcasting like how a dainty englishwoman sips tea while we empty our magicka bar just trying to kill one enemy of the same level range as us?