System shock is the generic term for the effects which cause destruction when using polymorph magic (including polymorphitis). Different effects happen to objects, monsters, and the player. In all three cases, the associated message is some variation on "shuddering." In real world terms this is perhaps better described as a massive trauma.
Objects have a chance of shuddering depending on type and beatitude. A wand or cursed object has a one in 3 (guaranteed for stacks of more than 4) of shuddering. An uncursed non-wand object has a one in 8 chance of shuddering. For a blessed object the chance is one in 12. The chance is doubled if the object stack is larger than 4 objects.
When an object shudders, randomly up to all but one, or one if there was only one object, is destroyed. For each object in the original stack, there is a one in (45 + Luck) chance of a golem being created. The golem type depends on the material of original objects, e. g. glass objects make glass golem, cloth objects make rope golem, etc. Bone objects create a skeleton instead, and if such golems or skeletons are genocided, a random monster is created instead. Only one golem (or other monster) can be created per square affected by polymorph. If a golem (or other monster) is created, then after all appropriate objects on the square have been polymorphed, and some were destroyed by system shock, more objects on this square are destroyed. If the monster weight is W, at most W objects can be destroyed. The game looks at each object, or stack of objects, in order from the top of the pile, and deletes it if it is of the same material as the object which shuddered to create the golem. (However, with 1/(W+1) chance, the object or stack will only be deleted if it is not of the same material.)
Amulet of Yendor, Candelabrum of Invocation, Bell of Opening, Book of the Dead, rider corpses, and scroll of mail never cause system shock, and are protected from destruction if another object caused it..
Monsters have a one in 25 chance of dying without leaving a corpse when hit by a wand of polymorph, polymorph spell, or potion of polymorph. The test is done after the tests for magic resistance. Chameleons, doppelgangers, and sandestins are immune, unless the hero has protection from shape changers .
The player is not subject to instant destruction like the other classes of polymorphable things. Instead, when you polymorph randomly, you have (1-constitution/19) chance of experiencing a system shock. If this happens, you lose 1d30 hit points and abuse your constitution. This effect will not occur if you have polymorph control, have lycanthropy, are a vampire or vampire bat, or wear dragon scale mail or dragon scales.
- "You feel shuddering vibrations."
- A polymorphed object has undergone system shock
- "The <monster> shudders."
- A polymorphed monster has undergone system shock
- "You shudder for a moment."
- One possible reason is that you have undergone system shock