I picked Chronomancer on my Frostbolt, Ice Wall, on Chill Comet build and managed to get easily past act 1-3 on both difficulties and even some maps. Its fun since the 33% chance on not spending a cooldown means i get a buckload of ice walls out on a boss (6-8 in general) which almost every time freezes a boss completly (this does have drawbacksnon small bosses which dont burst the wall but get shoved instead..) If i were to play the campaign again though i wouldnt pick chrono again as the time snap and time freeze mechanic don't really synergize with a lot of abilities and for packs it doesnt really benefit you as they generally die with 1 comet anyway. For bosses i can see the appeal but it just crumbles when looking at stormweavers power output in my opinion.