This spell allows you to scribe a potent rune of power upon a surface. When triggered, a symbol of sleep causes all creatures of 10 HD or less within 60 feet of the symbol of sleep instead fall into a catatonic slumber for 3d6 × 10 minutes. Unlike with the sleep spell, sleeping creatures cannot be awakened by nonmagical means before this time expires. Once triggered, a symbol of sleep remains active for 10 minutes per caster level.

Until it is triggered, the symbol of sleep is inactive (though visible and legible at a distance of 60 feet). To be effective, a symbol of sleep must always be placed in plain sight and in a prominent location. Covering or hiding the rune renders the symbol of sleep ineffective, unless a creature removes the covering, in which case the symbol of sleep works normally.

As a default, a symbol of sleep is triggered whenever a creature does one or more of the following, as you select: looks at the rune; reads the rune; touches the rune; passes over the rune; or passes through a portal bearing the rune. Regardless of the trigger method or methods chosen, a creature more than 60 feet from a symbol of sleep can't trigger it (even if it meets one or more of the triggering conditions, such as reading the rune). Once the spell is cast, a symbol of sleep's triggering conditions cannot be changed.

In this case, “reading” the rune means any attempt to study it, identify it, or fathom its meaning. Throwing a cover over a symbol of sleep to render it inoperative triggers it if the symbol reacts to touch. You can't use a symbol of sleep offensively; for instance, a touch-triggered symbol of sleep remains untriggered if an item bearing the symbol of sleep is used to touch a creature. Likewise, a symbol of sleep cannot be placed on a weapon and set to activate when the weapon strikes a foe.

You can also set special triggering limitations of your own. These can be as simple or elaborate as you desire. Special conditions for triggering a symbol of sleep can be based on a creature's name, identity, or alignment, but otherwise must be based on observable actions or qualities. Intangibles such as level, class, HD, and hit points don't qualify.

When scribing a symbol of sleep, you can specify a password or phrase that prevents a creature using it from triggering the symbol's effect. Anyone using the password remains immune to that particular rune's effects so long as the creature remains within 60 feet of the rune. If the creature leaves the radius and returns later, it must use the password again.

You also can attune any number of creatures to the symbol of sleep, but doing this can extend the casting time. Attuning one or two creatures takes negligible time, and attuning a small group (as many as 10 creatures) extends the casting time to 1 hour. Attuning a large group (as many as 25 creatures) takes 24 hours. Attuning larger groups takes an additional 24 hours per 25 creatures. Any creature attuned to a symbol of sleep cannot trigger it and is immune to its effects, even if within its radius when it is triggered. You are automatically considered attuned to your own symbols of sleep, and thus always ignore the effects and cannot inadvertently trigger them.

Read magic allows you to identify a symbol with a Spellcraft check (DC 10 + the symbol's spell level). Of course, if the symbol is set to be triggered by reading it, this will trigger the symbol.

A symbol of sleep can be removed by a successful dispel magic targeted solely on the rune. An erase spell has no effect on a symbol of sleep. Destruction of the surface where a symbol of sleep is inscribed destroys the symbol but also triggers it.

Symbol of sleep can be made permanent with a permanency spell. A permanent symbol of sleep that is disabled or has affected its maximum number of hit points becomes inactive for 10 minutes, but then can be triggered again as normal.

Note: Magic traps such as symbol of sleep are hard to detect and disable. While any character can use Perception to find a symbol, only a character with the trapfinding class feature can use Disable Device to disarm it. The DC in each case is 25 + spell level, or 30 for symbol of sleep.