Well , for trash packs you really can't sustain dps , we only have bursts from frozen orb/freeze and (optional) prismatic crystal. You should always pool 2 ice lances and use FB . The only exception is when your target is about to die , in that case use FB with the one ice lance proc (1 hit from FB>1 frost bolt). IN=3-4 FB , as you get gear they will become closer and closer and FB will pull ahead eventually , but for dungeons IN is better due to the interrupt aspect of it. You get the FoF proc when the frostbolt connects with the target , so you would see the second FoF usually at 50% o