A spellcaster with enough talent, resources, and inspiration can create a special variant of a golem known as a shield guardian. Any true golem can be created as a shield guardian, but the choice to do so must be made during the golem's construction—a completed golem cannot later be “upgraded” to function as a shield guardian.
Shield guardians are designed to serve as bodyguards. When created, a shield guardian is keyed to a magical amulet that is constructed at the same time as (and as part of the cost of) the guardian. Henceforth, it regards the wearer of that amulet as its master, protecting and following that individual everywhere (unless specifically commanded not to do so). If a shield guardian's amulet is destroyed, the guardian ceases to function until a new one is created. If the wearer dies but the amulet is intact, the shield guardian carries out the last command it was given.
A shield guardian obeys its master's verbal commands to the best of its ability, although it is not good for much beyond combat, protection, and simple manual labor. It can also be keyed to perform specific tasks at specific times or when certain conditions are met. The wearer of the amulet can call the shield guardian from any distance, and it will come as long as it is on the same plane.
Shield guardians have the same statistics as the base golem, but with the following additional special qualities.
Challenge Rating: A shield guardian's CR is equal to the base golem's CR + 2.
A shield guardian that has the berserk special attack cannot go berserk as long as the wearer of its amulet is within 30 feet.
A shield guardian has fast healing 5.
As long as a shield guardian and its amulet are on the same plane, the shield guardian can locate the amulet's wearer (or just the amulet, if it is removed after the guardian is called).
If ordered to do so, a shield guardian moves to defend the wearer of its amulet. All attacks against the amulet wearer take a –2 penalty when the shield guardian is adjacent to its master.
The wearer of a shield guardian's amulet can activate this defensive ability as a standard action if within 100 feet of the shield guardian. Just as the spell of the same name, this ability transfers to the shield guardian half the damage that would be dealt to the amulet wearer (note that this ability does not provide the spell's AC or save bonuses). Damage transferred in this manner bypasses any defensive abilities (such as immunity or damage reduction) the golem possesses.
A shield guardian can store one spell of 4th level or lower that is cast into it by another creature. It “casts” this spell when commanded to do so or when a predefined situation arises. Once this spell is used, the shield guardian can store another spell (or the same spell again).
A shield guardian's base materials cost an additional 25,000 gp above the base golem's cost. The creature's master may assemble the body or hire someone else to do the job. The Craft check required to make the body is 4 higher than normal for the base golem's kind. The keyed amulet is fashioned at the same time—it costs 20,000 gp above and beyond the shield guardian's total cost. After the body is sculpted, the shield guardian is animated through an extended magical ritual that requires a specially prepared laboratory or workroom, similar to an alchemist's laboratory and costing 500 gp to establish. If the creator is personally constructing the creature's body, the building and the ritual can be performed together. The creator must have a minimum caster level of 2 higher than the base golem's minimum required caster level. In addition, the following spells are added to the base golem's requirements: discern location and either shield or shield other.