Depends what enemy you're fighting. Against elites ice set is probably better as you're gonna proc the follow up once, but if you're fighting waves of enemies/an elite with spawns then probably the follow up set
her follow up attack is her weakest source of damage you'll need it to activate twice to even match her 1 of her skill damage (unless you do an elation run in su) the ice set we'll be better 90% of the time
Its a swarm disaster destruction thing. If you far enough along the path if destruction and you clear the first plane in a previous run, the first 4 enemy encounters will immediately drop to 1% hp.
