This spell allows you to scribe a potent rune of power upon a surface. Once triggered, the symbol of striking glows and lasts for 10 minutes per caster level or until it has made a number of attacks of opportunity equal to your level, whichever comes first. When triggered, the symbol threatens its area and the area around it as if it were a Medium creature wielding a magic version of the weapon you used as the material component. Using your caster level + 1 + your Intelligence modifier (magus, witch, wizard) or Wisdom modifier (cleric) or Charisma modifier (oracle, sorcerer) as its attack bonus, the symbol can make a number of attacks of opportunity each round equal to 1 + the same ability score modifier you used to determine its attack bonus. It gains a bonus on damage rolls equal to the same ability score modifier you used to determine its attack bonus. A shadowy version of you wielding the material component appears to make these attacks.

The symbol attacks any non-attuned creature that provokes an attack of opportunity from the symbol. However, when the symbol first attacks a creature, the symbol must overcome that creature's spell resistance or be rendered unable to harm it. The symbol never again attacks such creatures. Further, when the symbol first attacks a creature, a successful Will saving throw allows the creature to see the shadow nature of the attacks and take half damage when such attacks hit.

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

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

Symbol of striking can be made permanent with a permanency spell. A permanent symbol of striking 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 striking 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 striking.