Miscast effect

Version 0.28: This article may not be up to date for the latest stable release of Crawl.

A miscast effect occurs when a player fails to cast a spell successfully. These can range in severity from completely harmless to inflicting heavy damage and magic contamination, depending on the school of magic, the spell level, and the degree of failure. Players wishing to protect themselves from miscasts should focus on increasing the spell success rate, as this reduces both the frequency and intensity of miscasts. Additionally, miscasts from some schools of magic produce elemental damage that can be resisted.

The in game spell failure rate color indicates the maximum potential damage relative to your current max HP. These are calculated as if the damage is irresistible, even for those schools whose miscast effects are resistible or not directly damaging.

Color	Potential HP Loss	Warning Description
Grey	None	safe
White	0% - 10%	slightly dangerous
Yellow	10% - 30%	dangerous
Light red	30% - 50%	quite dangerous
Red	50% - 70%	extremely dangerous
Purple	70% - 100%	potentially lethal

The spell description shows the full list of possible miscast effects, including maximum damage and damage types.

Effects

Miscasting a spell from any school causes contamination based on the spell level and degree of failure (which can range from 1 to 99 for spells that are almost impossible to cast; higher success rate reduces the maximum range):

Contamination: (Spell Level × Spell Level × Degree of Failure + 250) / 500

If this results in more than 0.8 points of contamination, an additional effect is applied based on the spell school. If the spell has multiple schools, one of them is chosen at random. The intensity of the effect is rolled based on the spell level and the raw spell failure chance (an internal value from 1 to 99, not the failure rate shown on the spell list).

Intensity: (Spell Level)d(Spell Level + Raw Failure Rate) / 9

For damaging effects, this is the amount of damage done. For status effects (slow and dimension anchor), this is the duration in turns. Other effects as listed:

School	Effect
Air Magic	electricity damage
Conjurations	irresistible damage
Earth Magic	shrapnel damage (reduced by AC three times)
Hexes	debuff and slow
Fire Magic	fire damage
Ice Magic	cold damage
Necromancy	draining damage
Poison Magic	poison damage
Summonings	durably summoned nameless horror HD = 2 × Intensity / 3
Translocations	-Move
Transmutations	double current contamination plus 9 × Intensity / 1000 contamination

See Also

Magic contamination

History

• Prior to 0.28, miscast effects were applied to Hell's mystical force.
• Prior to 0.26, miscast Translocations inflicted Dimensional Anchor instead of -Move.
• Prior to 0.25, the miscast effect system was significantly more complicated, with three different types of effects per school, depending on the severity of the miscast. Many other effects, including divine retribution, became independent of miscasts in this version.
• In 0.16, many magic miscast effects received a significant overhaul.
• Prior to 0.14, Hell's mystical force could paralyze the player.
• Prior to 0.13, Zot traps inflicted a random severity 3 miscast, instead of having a hardcoded list of effects.