Ally-only.
Just as a general note, anything that's a targeted buff is ally-only, since you can't target yourself.
Sadly yea, it's ally only just like the shields.
MA Arcs: Yarmouth 1509 and 58812
Great question -- I agree, you want to be able to build your toon in such a way that it matches your particular playstyle as best you can.
I recommend getting in the habit of checking a resource (I use www.paragonwiki.com) if you have questions like this about specific powers, powersets, ATs, etc.
You can find some great information on the Frostwork power here at the wiki: http://paragonwiki.com/wiki/Frostwork#Frostwork
Good luck with your build, Cold Domination is a great and fun set! 
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StainedGlassScarlet - L50 Spines/Inv Scrapper | Badges: 1,396
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Thanks all! Thanks for the wiki link especially, most helpful. 
Also, you'll almost certainly want to skip that power unless it's an RP thing.
Check out http://boards.cityofheroes.com/showthread.php?t=124926 for the detailed explaination, but basically it's a pain to maintain and doesn't provide nearly as much of a benefit as the numbers say it does.
Does anyone know if this power is ally-only or if it can be used on yourself? The description doesn't mention. I only ask because I don't team-up often and wouldn't want to waste a slot on a power I'd barely use. Thank you.