Symbol of Insanity Spell
D&D Description of the Symbol of Insanity Spell : This spell functions like symbol of death, except that all creatures within the radius of the symbol of insanity instead become permanently insane (as the insanity spell).
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.
Deeper info on this Dungeons & Dragons Symbol of Insanity Spell
Note: Add a Reply about how you have applied the use of the Symbol of Insanity spell in a previous Dungeons & Dragons scenario.