Anti-magic field

^ anti-magic field
Generates	Anywhere
Effect	Pw loss, or HP loss if magic resistant

The anti-magic field (also known as the anti-magic trap) is a type of trap that appears in NetHack. It can sap away your magic power and even your health in some cases.

Generation

Anti-magic fields can be generated on most levels. They are also guaranteed on several special levels:

• The Knight quest locate level contains 7 anti-magic fields.
• The Wizard quest locate level contains an anti-magic field.
• Almost every special level in Gehennom has at least one anti-magic field.

Effects

Anti-magic fields drain between 2 and your experience level + 1 points of your spell power. If this would cause your spell power to go below zero, your maximum spell power will be permanently reduced by that amount, and your spell power becomes zero. Anti-magic fields have no effect on your maximum spell power if it is zero.

If you have magic resistance, you take damage instead of losing power. The damage is at least d4, with an additional d4 each if you:

• have half physical damage or half spell damage (non-cumulative)
• are wielding Magicbane
• are carrying an artifact which grants magic resistance by being carried; your own quest artifact is exempt.

If you have phasing, you take ¹⁄₄ of that damage, rounded up.

The following information pertains to an upcoming version (3.7.0). If this version is now released, please verify that it is still accurate, then update the page to incorporate this information.

As of commit 5c7c9d1, anti-magic fields now drain 2d6 energy and half that of maximum energy. If you have magic resistance, you take d4 damage in addition to the energy drain.

Effect on monsters

Monsters are only affected by this trap if they have a special attack such as spellcasting or a breath weapon; the timeout for their special attack increases by 2d2 turns unless they are magic resistant, in which case they lose HP. This will also reveal the trap.

Removal

When standing on an anti-magic field, you can dig down to replace it with a pit.

The following information pertains to an upcoming version (3.7.0). If this version is now released, please verify that it is still accurate, then update the page to incorporate this information.

As of commit c722962, anti-magic fields will explode if you zap a wand of cancellation or spell of cancellation at them.

Strategy

In theory anti-magic fields could be harmful to some early-game spellcasters, especially pacifists who must cast healing often and cannot gain experience easily; players who spend an early wish on a source of magic resistance may also be vulnerable. In practice, however, the trap tends to be a nuisance at worst.

Intentionally stepping on an anti-magic field is a somewhat risky way of identifying the cloak of magic resistance.

History

The anti-magic field was introduced in NetHack 1.3d.

Messages

You feel your magical energy drain away.

You are not magic resistant, and your Pw was drained.

You feel momentarily lethargic.

You are not magic resistant, but you have zero maximum Pw to drain.

You feel sluggish.

You are magic resistant, and took less than ¹⁄₄ your HP as damage.

You feel very lethargic.

You are magic resistant, and took more than ¹⁄₄ your HP as damage.

You feel unbearably torpid!

You are magic resistant, and were killed by HP loss.

<monster> seems lethargic.

A monster lost some Pw from an anti-magic field.

<monster> is killed by the compression from an anti-magic field!

A magic-resistant monster lost enough HP from an anti-magic field to die.