Fulminant Prism

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Version 0.29: This article may not be up to date for the latest stable release of Crawl.
Fulminant prism.png Fulminant Prism
Level 4
School1 Conjuration
School2 Hexes
Source(s) Book of Blasting
Book of Conjurations
Casting noise 4
Spell noise 0
Power Cap 200
Range 4
Flags Area, Not self, Target
Conjures a prism which unleashes a violent explosion of arcane force after a short duration. The prism is extremely fragile and any damage caused to it may result in premature detonation.
A slender prism that crackles with barely-contained destructive energy. Any blow which cracks its fragile surface is likely to result in a violent explosion.
Spell Details
Damage Formula
  • Normal explosion: 3d(6+Power*7/40)
  • Weak explosion: 2d(6+Power*7/40)
Max Damage 3d23 ~ 36
Max Power 200
Range 4
Targeting Smite
To-hit Never miss
Special Detonation radius:
2 (normal), 1 (weak)

Fulminant Prism is a level 4 Conjurations/Hexes spell which creates an explosive prism of the same name.

Conjurers start with this spell in their libraries.

Useful Info

Fulminant Prism creates a prism at an empty, smite-targeted location within its range. The prism will detonate with a radius-2 explosion after 20 auts, dealing considerable physical damage that can't be blocked or dodged (though reduced by AC as normal).

The prism can be damaged and destroyed by enemy attacks; it is rather frail, but immune to most elemental damage. If destroyed prematurely, the prism will create either a smaller, weaker explosion, or no explosion at all (if it is destroyed immediately after being created).

Fulminant Prism is considered a conjured entity, not an ally, so continues to function under Okawaru or Sacrifice Love.


Although you need to place your prism carefully to keep it from being destroyed by monsters, the smite targeting, large area of effect, decent damage output, and ability to blow things up beyond your line of sight makes it a very useful spell. Although there are more time- and MP-efficient methods for taking out powerful, well-armored opponents, it's excellent for wiping out swarms of smaller foes or taking out statues, oklob plants, and dangerous eyeballs from a position of safety.

Even as the damage starts to become uncompetitive, the prism itself remains very useful for blocking enemy line of fire. A shining eye can't Malmutate you through a prism, for example.

Tips & Tricks

  • Don't blow yourself up. If you set a prism 1 space in front of you, you can back up 2 tiles and be safe.
  • Monsters will only target the prism if it would block their intended movement. As the explosion is quite big, you can set it out of an obvious path, if so desired.
  • To hit a 10-speed enemy, you can set up the prism up to 4 tiles away, in the direction they are going. A prism set adjacent in a forwards direction will also hit the enemy. As enemies will fight in melee over avoiding the prism, you can position yourself and the spell to hit the now-stationary monster.


  • Prior to 0.14, Fulminant Prism was a level 5 spell.
  • Fulminant Prism was added in 0.12.