Trust me, you'll definitely want to level Hell Fire and Ice Storm. You should use the buff combination of Ice Shield and Elemental Ward.
Ice Shield help increase your defense. A level 25 Ice Shield was maybe around 45x defense or so.
Elemental Ward adds additional damage to all your elemental attacks. My combination was to cast Ice Storm to freeze monsters + additional damage from Ward and then cast Hell Fire before freeze fades (no additional damage from Ward for some weird reason but it's DoT). You start casting skills like Fireball and Lightning Arrow when the mob is running near you and Lightning Web when they're all around you. All those skills receive additional damage with Elemental Ward so helps.
The additional damage is pretty small but they do eventually stack up to help kill faster.