Sphere

Spheres, e, are a class of monster in NetHack. This class is made up of monsters that act like "living mines", always exploding upon death. They will self-destruct and harm you; they also blow on you if you kill them in melee. Dextrous players can sometimes dodge the explosions completely, while players with the correct resistance might not feel harm from the blast (though their inventory might still take damage).

Monsters in this class:

• e flaming sphere
• e freezing sphere
• e shocking sphere
• e gas spore

Gas spores e are different to spheres in that they will never attack you and explode only if attacked. However, gas spores explode in a 3-by-3 square, thus even if a character survives the blast, a nearby pet might die. Peaceful creatures caught in the blast also become hostile.

e Floating eye is represented by the same character as spheres, but their behavior is significantly different. Floating eyes do not self-destruct.

y Black light and y yellow light are not spheres, but they self-destruct in a similar manner.

In SLASH'EM, flame and freezing spheres can be summoned by the fire and ice mages respectively. Killing or attacking a monster with a flame sphere or freezing sphere will be treated the same as if you had attacked it directly; you gain XP, anger peaceful monsters, etc. They are, of course, useless if the opposing monsters resist fire or cold. Too much use can also cause swift extinction of the species.

Encyclopedia entry

 The attack by those who want to die -- this is the attack
 against which you cannot prepare a perfect defense.
                               --Human aphorism
       [ The Dosadi Experiment, by Frank Herbert ]