I just hit 33 and I'm running through NM no problem (granted, it's only Act 1 NM). But I use Sweeping Wind (ridiculous!) and Fire Ally (can't wait for air). Crippling Wave is my main attack and the only 'defensive' skills I have is Breath of Heaven.
I've not run into any issues with any champion or boss packs. But again, it's just Act 1 NM. I'm all about the AOE abilities with this game as the packs seem to come in dozens not just 1 or 2. For big bosses or battles, I'll use 7SidedStrike.
Crippling Wave with its 3rd strike slowing attack speed and walk speed is pretty darn nice. And the resolve passive takes care of most of it. My gear isn't great, but I'll eventually stack some attack speed and life on hit to keep the flow constant.