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Mastering Magic / Building and Modifying Constructs

Construct Modifications

Source Ultimate Magic pg. 113
Standard constructs can be modified to enhance their base abilities, alter their appearance or function, or perform a variety of tasks beyond the intentions of their basic designs. Performing a modification provides a construct's creator with a simple way to create a unique construct. A modification can only be performed while the construct is inanimate or nonfunctioning.

Performing modifications on one's own construct requires the Craft Construct feat, and the creator must pay any additional crafting requirements and/or costs associated with the modification. Completing a modification requires 1 day per 1,000 gp of the modification's base price (minimum 1 day).

A list of all construct modifications can be found here.

Basic Modifications

Source Ultimate Magic pg. 113
These modifications are used to alter a construct’s basic properties: Armor Class, Hit Dice, and weaponry.

Armor Modification: This modification adds an enhancement bonus to the construct’s natural armor bonus or adds a magic armor property. The cost for magical enhancements equals the cost for creating magic armor as described in the Core Rulebook.

Hit Dice Modification: Hit Dice represent the overall strength and power of a construct. They affect a number of subsequent abilities, including hit points, saving throws, and base attacks. Determine the effects of a Hit Dice modification using the rules for adding creature Hit Dice on pages 290–291 of the Bestiary. Because a construct’s size is limited, a Hit Dice modification cannot increase its size. Therefore Hit Dice modification can never increase the base construct’s Hit Dice beyond 50% of its total HD. Some constructs have a defined cost for increasing Hit Dice. To calculate the cost per Hit Die of other constructs, divide the construct’s construction cost by its existing Hit Dice.

Weapon Modification: This modification enhances a construct’s physical weaponry. This process includes adding actual weapons (such as blades or spiked chains) to the physical structure of the construct or enhancing existing weapons with additional magical properties. Structural changes alter the construct’s damage only. A construct is automatically considered proficient with any weapon added to its structure as a weapon modification. The cost for adding a weapon is determined by the cost of the weapon or weapon enhancement added. The cost for magical enhancements to these weapons is the same as the cost for creating magic weapons as described on page 468 of the Core Rulebook. Performing a weapon modification also requires the Craft Magical Arms and Armor feat.

Ability Score Modification: Using this modification, a crafter can permanently increase one of the construct’s ability scores by +2 per modification. He cannot increase any abilities with a score of 0. The cost for permanently increasing an ability score is 5,000 gp.

Complex Modifications

Source Ultimate Magic pg. 114
These modifications represent more complex changes to the structure and function of the construct. The cost is equivalent to the minimum level to cast the spell × the spell level × 250 gp.