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	5
Spell noise	15
Power Cap	200
Range	5
Flags	Area

Turns the air around the caster into a freezing vortex, doing tremendous damage to everyone caught in it that can only partially be 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. 5 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.