This spell allows you to scribe a potent rune of power upon a surface. When triggered, a symbol of vulnerability saps the defenses of all creatures within 60 feet. Affected creatures receive a –4 penalty to spell resistance and a –4 penalty on saving throws, and energy resistances and damage reduction (if any) are reduced by 10 each (to a minimum of 0). Once triggered, the symbol remains active for 10 minutes per level. The effects last as long as the creature is within 60 feet of the symbol, and for 1 round per caster level afterward.

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

As a default, a symbol of vulnerability 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 vulnerability 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 vulnerability'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 vulnerability to render it inoperative triggers it if the symbol reacts to touch. You can't use a symbol of vulnerability offensively; for instance, a touch-triggered symbol of vulnerability remains untriggered if an item bearing the symbol of vulnerability is used to touch a creature. Likewise, a symbol of vulnerability 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 vulnerability 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 vulnerability, 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 vulnerability, 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 vulnerability 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 vulnerability, 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 vulnerability can be removed by a successful dispel magic targeted solely on the rune. An erase spell has no effect on a symbol of vulnerability. Destruction of the surface where a symbol of vulnerability is inscribed destroys the symbol but also triggers it.

Symbol of vulnerability can be made permanent with a permanency spell by a caster of 18h level or higher for the cost of 25,000 gp. A permanent symbol of vulnerability 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 vulnerability 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 33 for symbol of vulnerability.