Well it depends a lot on your playing style.
Usually, when the Tanker arrives in the middle of mobs, I use Ice Slick under him, followed by Freezing Rain.
Then,
a) Glacier is ready. So I move close to the Tanker and freeze everything. Then I'd use a Bloc of Ice on a Boss. Next step would be Lightning Storm and Artic Air, so when the hold stops, they are slowed and confused. After the hold, you might have to use O2 Boost on someone.
b) Glacier isn't ready, so I use Shiver and Snow Storm, holding the anchor with a Bloc of Ice so my team mates know who to kill last.
You can also chose to use Frostbite and Tornado. Possibly with Thunder Clap. However it's not of my taste.
I have Steemy Mists with Superspeed. Also Hurricane, but I almost never use this one. I just can't use it well in pve.
And, well, obviously, Jack Frost.
Ice Control:
Must Haves:
1: Block of Ice, single hold, will be your most used power.
2: Ice Slick, super knockdown power (except against clocks!)
3: Glacier, your AoE hold
Useful:
1: Jack Frost, good dmg in melee but isnt too fond of going in there, has an ok hold aswell.
2: Shiver, nice wide cone slow
3: Arctic Air, really nice PbAoE slow and confuse. Unfortunately doesn't synergize too well with Hurricane and uses a LOT of end. You have to choose between this and some of the toggles from Storm because of the enduse.
Has it's uses:
1: Chillblain: Recommend taking this at the lowerlvls for dmg and maybe respec it out later. Still very nice to keep AVs in check in the later game.
2: Frostbite: Doesn't synergize well with both ice and storm because of the 10 second -knockdown in it (except if you're using Tornado). Very handy for setting up containment so definately consider it for the endgame.
Limited Use:
1: Flash Freeze, it's a sleep. Has it's uses but would vote against it...too many other good powers to take.
Storm Summoning:
Must Haves:
1: Gale: 'cos you have to take it 
(otherwise pretty [censored])
2: Snow Storm, very good to keep the mobs in your Ice Slick/Freezing Rain and for AV fights.
3: Steamy Mist, nice res (to limited dmgtypes tho) and stealth....throw super speed in your build and you're invisible to mobs ('cept snipers and such). Don't slot the def aspect of it.
4: Freezing Rain, very nice -res, -def, slow power + it has knockdown..WINNAR! (don't ever slot it for dmg!!)
5: Hurricane, one of the best accuracy debuffs in the game and will save your life on many an occasion...and it's fun 
6: Lightning Storm, good dmg, nice debuff and stun....great power.
Useful:
1: Tornado, pretty good dmg, excellent for AV fights, pretty good panicbutton. Seriously consider taking Frostbite if you plan on taking this 'cos the knockback (or more like knockallovertheplace!) is pretty insane.
Has it's uses:
1: o2 Boost, small single target heal. Personally kept Jack alive a lot longer with this one + it has a very handy resistance to enddrain so excellent for fighting malta.
Limited Use:
1: Thunder Clap, PbAoE stun that stuns only minions and has a horrid animationtime....looks well cool though
hmm, this got a little longer than expected but hope you can use it?
(note this is PvE related suggestions!)
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CRACK68:
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Lionsbane:
"You know me.Ever the realist"
I'd put AA as a must have for ice control, along with Ice slick and block of ice. Glacier is very handy, but its reduced duration and increased recharge have certainly put it behind Ice Slick for being good AoE control.
Flash Freeze, I'd say HELL NO, Ice Slick wakes them up, you'll be using Ice Slick often, probably as often as you can. Frost Bite also doesn't work well with Ice Slick, normally enough to grab all the agro to you before it the knock down kicks back in.
"Well, they found my diary today.
They were appropriately appalled
at the discovery of the eight victims
They're now putting it all together.
Women wrapped in silk
with one leg missing
Eight legs, one body, silk,
spider, brilliant!"
Must-Haves:
Hurricane
Ice Slick
Block Of Ice
Freezing Rain
Snow Storm
Jack Frost
Glacier
Everything else is extra, although all storm powers are useful, apart for O2 and Thunder Clap.
O2 is useful for keeping your pet alive and its very useful against KoA and the like. Its certainly better than the medicine pool heals, for example. Gale is useless though (but you get it anyway)
Personally I think Tornado is one to check before you get (try on the Test Server 1st).
What powers are must haves, what are must nots?
Only on level 8 at the moment but I know nothing about either set apart from facing them in PvP. This character will certainly be PvE only until I hit at least mid thirties. So any helpful hints would be appreciated.