i have been playing as a stock nightblade which has the school destruction. but i very seldom use that skill. so what destruction spells are folks here casting?

My main uses for destruction:
1. Weakness to Magicka- when it comes to enchanted items this usually lets you pack more punch for your EP if you put it first.
2. Drain various skills on Self- used with tricksy training.
3. Drain Intelligence fully on Self- bam, magic meter's brimming full. I'm currently going through the motions in a new game and my magicka resistance is up to a full-time 70 percent now so I use this much less often.
4. Straight-up damage health- when I've already shoved absorb health onto a spell/enchantment and have room for more.
5. Check the sig I'm about to make.

Damage Attribute is also worth a look. Damage speed 10 for 5 sec can stop a Golden Saint (speed 50) for target practice with either a bow or a spear and it doesn't hurt if it gets reflected.

Another relatively low cost spell is fire damage 25 target in 50' ; a couple of these will clear out most tombs very efficiently.