Electric mastery works very well with the Ice primary as it gives you a second fast activating, fast recharging hold. This means you can lock down your bosses from a range and keep them locked down whilst still dealing with the rest of your foes. I have this on my Ice/En and this and the armour were my sole reasons for choosing the set.
The armour is arguably the most useful of the three as it provides energy resistance, another very common damage type, especially in PvP. Definitely a good bet.
I haven't experimented with the other two, for the following reasons. The cone didn't fit my single target build. I imagine it has potential with Ice/Ice as all the slows may well be good for keeping your foes inside Ice storm, and then you could unload with Frost Breath and the epic cone (it's name has slipped my mind). As for EM Pulse, although it seems pretty damn cool, the huge recahrge is enough of a turn off to make other powers seem worth while.
Hope some of that helps!
On my blaser, if I was to change epic, it would be to Ice for more a PvE build than I have currently. I mainly plan to get it for snowstrom to allow for more AoE potential, but I'm not completely sold on it yet. SO I will be watching this thread too!
Snowstorm is excellent, absolutely excellent. Minus fly and a slow, combined with Shiver you can bring everything and anything to a crawl, helps you with using Ice Storm regularly without annoying the team, which ups your AOE damage potential lots, overall very nice. It eats endurance though, and definitely needs slotting for it. Be prepared to carry blues for AV fights if you're not having your endurance boosted.
Hibernate is useful for panic button and/or a quick end recovery burst (no slotting needed, the end and health recovery are very nice, if you really have slots free it could take a recharge or two).
The armour is not awesome, not enough defence to really get excited about, on a PvE build on my Ice/Ice I actually specced the armour out simply because with the level of control available in the build, I didn't need it. I also didn't feel it was good enough to warrant the endurance cost.
Flash Freeze is excellent for safe soloing on a good single target set. If you want to and have the slots free you can pretty close to chain sleep stuff with it, or just slot it lightly and use it as a panic button/opener. However, it is relatively little use in teams except as an occasional panic button if a second group is aggroed (and get ready to deal with the full aggro of the group when they wake up).
Overall, Ice/Ice/Cold is generally quite nice for a controllery build on a blaster.
Well I just got my Ice/Ice powersuited police officer known as Icen to 41, and therefore can take an Epic set.
Proximity took Force, cos she was Energy/Energy. I love it, and wouldn't swap it for any of the others. But I've done Force, and need another Epic.
Now, it has to fit thematically with the powersuit concept, which to my mind makes it a straight choice between Cold Mastery and Electric Mastery.
Flash Freeze looks quite interesting, I've used Snow Storm before on my Grav/Stormie, Frozen Armour is OK, and Hibernate, well, I guess it's an alright panic button. No Force of Nature, but then, what else is?
Electric Mastery I may be able to get away with too, cos of the powersuit concept. However I know a lot less about this one. I don't need another hold though.
Any thoughts? Any experiences with the individual powers?