Magic contamination

Version 0.29: This article may not be up to date for the latest stable release of Crawl.

Magic contamination is a dangerous condition caused by miscasts and some magical effects.

Overview

Various activities cause harmful magical energies to accumulate in your body. A small amount of magical contamination (a dark or light grey "Contam" status) is mostly harmless, and will dissipate over time without any further effect. Larger amounts of accumulated magic contamination (a yellow, red, or dark red "Contam" status) will make you start to glow with magical contamination.

Contamination over 5 points is considered severe. Being at a severe contam level makes you easier to hit and reveals you if invisible, similar to the Corona spell. It also leaves you at risk to bad mutations and damaging explosions.

Any amount of contamination can cause ugly things adjacent to you change their colour.

Contamination Levels

Contam	Colour	Description
>0	Dark grey	You are very lightly contaminated with residual magic.
3	Light grey	You are lightly contaminated with residual magic.
5	Yellow	You are contaminated with residual magic.
15	Light Red	You are heavily infused with residual magic.
25	Red	You are practically glowing with residual magic!
40	Red	Your entire body has taken on an eerie glow!
60	Red	You are engulfed in a nimbus of crackling magics!

Note that this page (and the rest of the wiki) refers to contamination as points. In the source code, contamination is listed as 1000x greater than here.

Sources

Spells

• Irradiate: 1.25 to 2 per cast

Spell Miscasts

• Every miscast: Depends on the miscast severity. See Miscast effect#Effects for more information.
• Transmutations miscast: Doubles current contam

Other

• Invisibility (ego): (?)
• Removing an artefact with *Contam: 7
• Mutagenic fog: 1.3 to 2.55
• Zot trap: 7 to 20 (one of many possible outcomes)
• Jiyva penance: 0 to (0.5 * penance) (one of many possible outcomes)

Dissipation

Magic contamination is dissipated at the rate of 0.075 per turn. Quaffing a potion of cancellation instantly removes 1 to 5 points of contamination.

While being severely contaminated every 70 - 200 turns there is contamination / 12 chance of a violent release of energies. Standing in Zin's Sanctuary stops this from happening.

One likely bad mutation (about 95% chance) is gained that bypasses mutation resistance. If contamination is higher than 10, there is also a damaging explosion. The damage is 3d(contamination / 2), and doubled for the non-living. Explosion size also increases with the contamination level. After the negative effects, contamination is reduced by 1 to (1 + contamination / 4).

Tips & Tricks

Being in lichform, by way of Necromutation, prevents any contamination-related malmutations; instead, your stats temporarially rot.

History

• In 0.29, the level of contam for the light grey warning was decreased from 3.5 to 3, to match Irradiate's increased contam.
• Prior to 0.28, the Orb of Zot extended contamination.
• Prior to 0.26, magic contamination decayed much slower: -0.025 per turn instead of -0.075, while the time between bad effects was also slower (200 - 600 turns).
• Prior to 0.25, miscast effects were different, and thus had different contam levels.
• Prior to 0.19, the light grey contamination level didn't exist.
• Prior to 0.10, this effect was simply called glow, a ambiguous term that also referred to the backlight caused by Sticky Flame and Corona (and contam itself).

Sources of Contamination

• Prior to 0.28, invisibility caused contamination over time, and Disjunction had .75 - .799 contamination on cast.
• Prior to 0.26, reading a scroll of blinking contaminated the player.
• Prior to 0.20, drinking a potion of haste contaminated the player, and the haste effect caused contamination over time.