Rimeblades

Ice Spell, Tier 4, 3 Actions, AoE

Concentration: Up to 1 minute. Reach: 12. Conjure razor-sharp icy spikes in 5 contiguous spaces within Reach; this area is difficult terrain. Creatures that enter these spaces (or who are in the area when you conjure them) suffer 2d6 damage for each space they touch. Upcast: +1 space, +1 damage.

From Core Rules