Polar Vortex

Version 0.30: This article may not be up to date for the latest stable release of Crawl.

Polar Vortex
Level	9
School1	Ice
Source(s)	Book of Ice
Casting noise	9
Spell noise	0
Power Cap	200
Range	5
Flags	Area, Destructive

Turns the air around the caster into a freezing vortex, doing tremendous damage to everyone caught in it that can only be half-mitigated by resistance to cold. Those affected will also be swept up into the air and tossed around. Only the eye of the storm is a safe place, and it follows the caster. The vortex is unable to follow the caster through long-distance translocations. The spell's effectiveness is greatly diminished in closed areas. After the vortex fades, it cannot be called forth again for a short time.

Polar Vortex is a level 9 Ice Magic spell that creates a frenzy of raging wind up to 6 tiles around you, dealing catastrophic cold damage.

Useful Info

Polar Vortex creates clouds of raging wind, dealing a base of 12d(pow/15) damage per turn. Only 50% of damage is affected by cold resistance. Twisters are the only monster completely immune to the vortex.

The damage is then adjusted by:

• Percentage of tiles open. In tight spaces, damage is reduced. Damage is multiplied by the ratio, (tiles with wind) / (tiles that could have wind).
• "Duration-radius" factor. Creatures on the outside of the Vortex will receive the most damage.

Polar Vortex also causes monsters (including orbs of destruction) and clouds to rotate around in a counterclockwise fashion. The "rotation" is in a square shape, done at a rate of (about) 1 full rotation per 6 turns.

While casting the spell, the caster and anything caught inside will fly for a short period of time. Once it ends, there's a grace period of ~2 turns until flight ends. Also, casting Polar Vortex makes the caster immune to other creatures' Polar Vortex.

Polar Vortex lasts for 6 turns. The vortex immediately ends if you blink or teleport via any means. After it ends, it has a cooldown of 3.5 - 4.5 turns. The vortex's radius is equal to sqrt(aut_passed) * 7/5, max. 6 tiles.

Tips & Tricks

• While Polar Vortex is less impressive than other level 9 spells, it is quite MP-efficient, as it only consumes MP on the turn it is cast. It also takes only one spell school to train.
• When the radius is 6, the amount of noise is 15. This number is multiplied by the delay of your last action (in auts) and divided by 10.
• Any trees within Polar Vortex's range have a chance of being destroyed by the spell.
• Be careful not to use Blink while the spell is up unless you specifically want to end its effects.

History

• Prior to 0.30, Polar Vortex was 60% irresistible.
• Polar Vortex was added in 0.27, as a rethemed version of Tornado. Comparative to Tornado, Vortex deals 33% more damage, but is partially resistible. In addition, a few monsters lost rTornado.