Torrential Avalanche
Tier 2 Epic evocation
Casting Time: 1 action or 10 minutes
Range: Sight
Components: V, S, M (a snow globe containing a tiny village at the base of a mountain)
Duration: 1 minute or 1 hour
A gigantic avalanche of snow and debris appears at a point you choose within range. You can make the wall a straight line up to 500 feet long, 100 feet high, and 50 feet thick. The wall lasts for the duration. When the wall appears, each creature within the area must succeed on a Strength saving throw or take 10d10 cold damage or half as much on a success.
At the start of each of you turns after the wall appears, the wall, along with any creatures in it, moves 60 feet away from you. Any Gargantuan or smaller creature inside the wall or whose space the wall enters when it moves must attempt a Strength saving throw or take 10d10 cold damage or half as much on a success. A creature can take this damage only once per turn. If the wall lasts for its full duration, it crashes to the ground in wave of frigid cold. Each creature within the wall’s area when the spell ends in this manner must succeed on a Dexterity saving throw or take 30d10 cold damage, or half as much on a success.
A creature caught in the wall can move by swimming. Moving within the wall costs quadruple movement. A creature that moves out of the area falls to the ground.
This spell can be cast with a casting time of 10 minutes. If cast in this way, the duration of the spell increases to 1 hour, and the wall may be a straight line up to 1 mile long, 500 feet high, and 100 feet thick. The wall moves 200 feet away from you at the start of each of your turns.
Ref: ELCR p104-105