Symbol of Insanity
School enchantment (compulsion) [mind-affecting]; Level cleric 8, sorcerer/wizard 8
Components V, S, M (mercury and phosphorus, plus powdered diamond and opal worth a total of 5,000 gp)
Saving Throw Will negates
Unlike symbol of death, symbol of insanity has no hit point limit; once triggered, a symbol of insanity simply remains active for 10 minutes per caster level.
Note: Magic traps such as symbol of insanity are hard to detect and disable. A rogue (only) can use the Perception skill to find a symbol of insanity and Disable Device to thwart it. The DC in each case is 25 + spell level, or 33 for symbol of insanity.