Ice Pike.
Ice Bolt is not bad, but its better for it’s freeze than damage, need high level to “instant”-cast.
Gust level 1, has 3 hits already and scales poorly, removes freeze which you don’t want so mostly a filler.
Snow Rolling and Frost Pillar are what you want to MAX for your damage, both are good at level 5, allied with Ice Pike and Subzero Shield (reflects damage). These skills are what you will really want to use when you get in late game. Mostly Frost Pillar with Pass is like the best CC for Earth Tower (not sure though?).