Whirling Slash on the spear from level 1 · Glacial Bolt from level 24 · the endgame skills all through the campaign, damage tree in the campaign and a respec at 79The Frost Cyclone

The final build is already the level 1 build: the spear spins and breaks the ice, the crossbow freezes and plants the crystal walls. Tell it your level and what you already have, and the guide shows what to do now, gem by gem, item by item, up to the endgame Whirling Glacial Bolt (one tree respec at 79).