You can't "make" Destruction powerful. No amount of planning makes up for terribly implemented direct damage spells that do less damage than bows over time, or even less compared to sneak attack bow shots. Reducing the cost of your spells doesn't make it "powerful" either, it just means you can cast indefinitely. Most spells that matter still have too long of a casting time.
Destruction svcked at high levels, with Oblivion too. And it's true, that not spending any magicka does NOT make it more powerful. So, you can whittle away at the boss and never run out of magicka? You won't get the chance to...it will kill you first. With no heavy or even light armor and no shield, and little health, because it all went into magicka at lower levels.
In Oblivion I supplemented Destruction with Illusion and Conjuration. But even command and control spells became less effective at higher levels. The only thing that DID NOT become less effective was Invisibility and Chameleon, and in the end I didn't even try to kill the mobs, because they would kill me. I just ran past them invisible. If I HAD to kill something, I used Conjuration. Because the summoned mob levels scaled like the mobs level. I'd summon one, then turn invisible.
But now it's been decided that Illusion made the came too easy, and they nerfed it, so you stuck with a destruction cap, and fewer options to supplement it. You try to use invisibility now, and the mob can still hear you and attack you like normal. And you can't cast control humanoid to make them stop. You can just cast rage/fury spells...which makes them madder and they still keep killing you.