Can you cast a spell with a duration of instantaneous inside a antimagic field?

For example, a wizard casts prismatic sphere (center circle) Four wizards around it cast antimagic sphere outside (outer circles).

If a bad wizard enters one of the antimagic fields and casts Mordenkainen's Disjunction, does it destroy the prismatic sphere? If it is cast outside the antimagic field does it destroy the prismatic sphere?enter image description here


3 Answers 3


A Disjunction cannot be cast within the Antimagic Field but a Disjunction cast outside the fields might work

From the text of Antimagic Field:

The space within this barrier is impervious to most magical effects, including spells, spell-like abilities, and supernatural abilities. It prevents the functioning of any magic items or spells within its confines.

From the text of Mage's Disjunction:

All magical effects and magic items within the radius of the spell, except for those that you carry or touch, are disjoined.


You also have a 1% chance per caster level of destroying an antimagic field. If the antimagic field survives the disjunction, no items within it are disjoined.

The wording leaves room for ambiguity, the following is my interpretation:

  1. No spell, not even Disjunction, can be cast while already within an antimagic field. ("It prevents the functioning of any spells within its confines.")

  2. If the Disjunction is cast from outside, it has a 1%/level chance of destroying each antimagic field in its area. If all the antimagic fields survive, they block it from reaching the Prismatic Sphere in the center. Note that Disjunction has a burst radius; thus, even if all four fields are within 40 feet of its origin, they are not necessarily within its area of effect.

  3. If at least one antimagic field breaks and exposes a portion of the prismatic sphere (in such a way that the Disjunction has an unobstructed line of effect from its origin, as per Burst radius), the sphere is instantly destroyed as well. ("All magical effects.... are disjoined.")

  4. If no antimagic field broke or the broken fields do not give the Disjunction line of effect to the sphere, it survives. (The wording in Disjunction only refers to items, but I believe this is an oversight as the spell is intended as an item destroyer and not a mere dispel.)


The Rules Compendium does not prohibit spellcasting within an area of antimagic but does say a spell's effect is either suppressed or negated if a spell's point of origin is within an area of antimagic...

The Rules Compendium on Antimagic says

Spells don’t function in an antimagic area, but an antimagic area doesn’t block line of effect. If a spell’s point of origin is inside an antimagic area, that spell is entirely suppressed. When a spell’s point of origin is located outside an antimagic area, but part of that spell’s area overlaps the antimagic area, that spell’s effect is suppressed where the two areas overlap. Time elapsed within an antimagic area still counts against a spell’s duration.

If an instantaneous spell is entirely suppressed, that spell is effectively canceled. (It’s suppressed, and its duration instantaneously expires.) An instantaneous area spell is only entirely suppressed and effectively canceled if its point of origin is within the antimagic area. Otherwise it works like any other area spell that has a point of origin outside the antimagic area—only where its area overlaps the antimagic area is its effect is suppressed (and effectively canceled). (11)

So the caster of the 6th-level Sor/Wiz spell antimagic field [abjur] (PH 200) (in addition to anyone who joins the caster within the field) has all magic suppressed while the field remains, but the caster doesn't actually lose the ability to cast spells or anything. Instead, spells that are cast are suppressed while the field remains or, if instantaneous, "effectively cancelled" if their points of origin are within the field.1

Thus, as per the illustration, when a caster enters one of those antimagic fields and casts the 9th-level Sor/Wiz spell Mordenkainen's disjunction [abjur] (PH 255), that caster picks the disjunction spell's point of origin. If he picks as the spell's point of origin a grid intersection covered by an antimagic field, the disjunction spell will fail. If the caster picks a grid intersection in the midst of the prismatic sphere, the spell will also fail as the caster lacks both line of sight and line of effect beyond the sphere.

The Range: Close of the spell Mordenkainen's disjunction means the caster's far better off picking as the point of origin for the disjunction a grid intersection above this excessively complicated, high-powered, volatile concentration of overlapping spell areas and seeing if the disjunction's 40-ft.-radius burst takes out any of the antimagic fields (1% per caster level) in addition to dispelling the prismatic sphere.

...But the Dungeon Master's Guide strongly implies that spells can't be cast spells in an area of antimagic

The Dungeon Master's Guide on Antimagic says

No supernatural ability, spell-like ability, or spell works in an area of antimagic (but extraordinary abilities still work). (290)

Lawyering the word works here becomes the issue,2 but later authors and editors likely believed this line (and, presumably, other evidence or house rules or whatever) significant enough to engender the creation of...

  • the feat Initiate of Mystra (Player's Guide to Faerûn 81): "You can... cast spells even within... an antimagic field [by making] a successful caster level check against a DC equal to 11 + the caster level of the antimagic field."
  • the 9th-level Sor/Wiz spell invoke magic [evoc] (Lords of Madness 212): "Within the area of an antimagic field, a dead magic area, or a null-magic plane... you [can] cast a single spell of 4th level or lower, which then ends [this] spell’s effect."

While both these artifacts are 3.5, both Player's Guide and Lords predate the Rules Compendium. Further, keep in mind that the entry on Antimagic from the Dungeon Master's Guide (2012) is verbatim the Antimagic entry from the Dungeon Master's Guide (2000) for Dungeons and Dragons, Third Edition, which had folks reading antimagic field as blocking line of effect.

Avoid problems by not using areas of antimagic

You can read the fights that the spell antimagic field creates in these threads from 2006,3 2009, 2010, 2011 (Warning: 9 pages!), 2011 (Warning: for Pathfinder—and the same problems), 2012, and 2013. These are merely a handful of the many threads just about casting spells in an antimagic field; there exist many other threads about the vast number of other antimagic field issues.

Thus, while picking either of the above readings (or developing another) is a solution if a campaign must incorporate areas of antimagic, I suggest not using areas of antimagic at all. Almost any discussion will lead to an argument and, usually, less fun for someone. It's an effect that makes no one happy, and almost any campaign is better off without it.4

1 The Rules Compendium on Out of Sight? No Problem! says, "For ranged attacks and other effects that originate from a creature, the point of origin is any corner of any square that the creature occupies" (80).
2 The Rules Compendium also says, "No supernatural ability or spell-like ability works in an antimagic area" (as does DMG 90). Then, immediately after, the RC adds, "Their effects are affected like spells" (11). This is singularly unhelpful.
3 Noteworthy in predating the Rules Compendium and citing the Third Edition FAQ that apparently said antimagic field does (or, that is, did), in fact, block line of effect.
4 Beholders can do other things with their central eyes.


Antimagic Field + Spells

An invisible barrier surrounds you and moves with you. The space within this barrier is impervious to most magical effects, including spells, spell-like abilities, and supernatural abilities. Likewise, it prevents the functioning of any magic items or spells within its confines.

An antimagic field suppresses any spell or magical effect used within, brought into, or cast into the area, but does not dispel it. Time spent within an antimagic field counts against the suppressed spell’s duration.

Summoned creatures of any type and incorporeal undead wink out if they enter an antimagic field. They reappear in the same spot once the field goes away.

A lot of people think that Antimagic Field stops spells being cast inside it - this is actually untrue.

What it actually does is suppress the effects and 'functioning' of magic items and spells that are inside the area of the field - whether they were cast within it or cast outside and entered it.

The key part that is interpreted to mean that magic cannot be used at all inside an antimagic field is this -

The space within this barrier is impervious to most magical effects

This is read to mean that spells cannot be cast or have any effect inside the field, instead of being suppressed. However, a spell effect is not the spell itself - this is spelled out in the 'Magic' chapter of the 3.5e PHB. Similarly, 'effect' is used consistently throughout 3.5e to refer to the effects, often the continuing effect, of a spell or ability.

Ergo, the most logical reading under RAW is that while you can cast spells inside an antimagic field, the effects of those spells are suppressed. So you could, for example, cast Summon Monster and summon a monster outside the area of the antimagic field.

Or cast Dispel Magic aimed at a person, magic item, or area outside the antimagic field (note that if the area overlapped with the antimagic field, the spell's ENTIRE effect would not work - not just the bit overlapping the field).

Antimagic Field does not break line of effect under this reading of what 'impervious' means in that context. Ergo, in the above example, someone outside the antimagic fields could aim a mordenkainen's disjunction at the prismatic sphere. Assuming the MDJ failed to shatter the AMF, though, the question becomes whether or not the prismatic sphere's 'stops all spells' ability would interact with the fact that the MDJ's 'effect' was suppressed by the AMF at the point the MDJ reached it. Would the MDJ's normal exception to the Prismatic Sphere's stop spells/effects effect, work while it was suppressed by the AMF (the point at which it makes contact)? Given the prismatic sphere stops the AMF at it's border, is there a moment where the MDJ stops being suppressed and then has it's effect of destroying the sphere?

That's purely a GM call at that point, as it's too much of an edge case.


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