Fire with TirRal Staff through normal.
Without immunities and high resistances fire is extremely strong, and works still pretty good until Act2-3 in nightmare.
When getting first Spirit Respec into Lightning Nova. Can be done early NM or later depending on the preferred playstyle.
Max out Nova + Static + some points in lightning Mastery.
Meanwhile built cold tree up to frozen Orb + one point into mastery.
Continue maxing Nova + Orb, which should carry you through the campaign and let you far most terror zones.
After campaign farm terror zones for cold sunder, and when you get it use second respec to built into cold.
Maxed out cold lets you play everything. You could stay cold or farm the necessary gear for other builts.