I see you love Slow Time. I hate it, it drags out the game like Quick Reflexes, and Steady Hand, and one of my favourite things about games like this is the White Knuckle Action.
My top 3 are:
Whirlwind Sprint, hands down. Virtually all of my characters have this mapped to the Powers key by default. I switch to others, but whenever I do, it's from Whirlwind Sprint. Why? First of all, it's a unique effect, there's nothing else like it in the game (Until you get Bats, which is Whirlwind Sprint for Vampires, with Bats.) Second off, I couldn't help but notice there's a lot of running cross country, and it goes a lot faster if you yell "Wuld!" as often as you can to speed things along. More Combat, less running around between fights, 'nuff said. And finally, it's a great way to get out of the melee when you're surrounded, and getting pounded on. I rarely, if ever play a capped out tank, and even when I did (Tried it, maxing 1 attack for the damage race turns into a boring spamfest with a quickness. "My fighting style is hit him over, and over until he dies!" Yawn.) you can still get in over your head, and need a moment to regroup.
Aura Whisper:
Any Stealth based build is most effective when you see them first. Also helps targeting with the unholy evil combo of Flaming Familiar>Ice Storm around, and through cover. If you're standing behind a rock, armor, and health don't matter, because they hit the rock, and you don't take any damage. Works on every NPC, and doesn't take Magicka, even IFFs for you, and really helps hunters spot game through underbrush (Not to mention not being ambushed by Sabercats.)
Ice Form:
Shut up, Ancano. There's lots of times when I really don't want to fight, or at least get a head start on the Damage Race when Stealth is not an Option. Beefgate bosses that you have to talk to first, so they force you to take them on in a toe-to-toe Duel? (Tsun, I'm looking at you.) In a Word, "Iiz," you can pound on them while they get up, then worry about Hack&Bash tactics, or run away, and pelt them with arrows from afar, or hose them down with Wall of Flames/Frost. For pretty much any character except the Smithed up Tank with the Sword of Earthcleaving, this gets you out of, or at least through the start in these fights where they leave you no choice. The Caller is a long frustrating Shell Game Boss that I've done a thousand times before, and sometimes would much rather cut short. If I don't happen to have Flaming Familiar/Ice Storm to 1 Shot her with, this keeps her from 'porting, summoning, and kiting me around the room while her Atronachs make life difficult for me.
In DLC, I'll add Cyclone. It's even more abusable fun than FRD.