Ice first i/l build (3rd job)

This was pretty much what I did, only with the last two points of Ice Strike after 11 booster, cold beam maxed (with ice wand) after Amp, and max booster for timer after that.

Otherwise, go with it.

I thought about that, but I decided that after spending so many levels with lvl 11 Booster, I'd probably be fine with keeping that for a while. Meanwhile, Seal and Partial Resistance allow you to hunt certain monsters that you'd normally have a tough time dealing with whether due to strong magic attacks/dispel or ice/lightning affinities. Of course generally there's very few events that would require that, but CGs and the Gold Box event show that Nexon may very well do similar things in the future. However, just to be clear, after you max IS, max EA, and have 11 Booster, there's really nothing that needs to be maxed immediately so it's just a matter of preference.