Improved simulacrum creates an illusory duplicate of any creature. The duplicate creature is partially real and formed from clay. It appears to be the same as the original, but it has only 65% to 85% of the real creature’s levels or Hit Dice (and the appropriate hit points, feats, skill ranks, and special abilities for a creature of that level or Hit Dice). You can’t create a simulacrum of a creature whose Hit Dice or levels exceed twice your caster level. You must make a Disguise check when you cast the spell to determine how good the likeness is. A creature familiar with the original might detect the ruse with a successful Spot check (opposed by the caster’s Disguise check) or a DC 20 Sense Motive check.
At all times the simulacrum remains under your absolute command. No special telepathic link exists, so command must be exercised in some other manner. A simulacrum has no ability to become more powerful. Improved simulacrum allows the duplicate to increase in power. The duplicate may advance up to four levels higher than the level it is created at. All of the rules for advancement and multiclassing apply to the duplicate as they would any character. If reduced to 0 hit points or otherwise destroyed, it reverts to clay and shatters instantly into nothingness. A complex process requiring at least 24 hours, 100 shillings per hit point, and a fully equipped magical laboratory can repair damage to a simulacrum.
Arcane material component: The spell is cast over the rough clay form, and some piece of the creature to be duplicated (hair, nail, or the like) must be placed inside the clay. Additionally, the spell requires a fire opal worth 100 shillings per Hit Die of the simulacrum to be created (minimum 1,000 shillings). The fire opal is placed inside the improved simulacrum's torso.
Experience point cost: 100 experience points per Hit Die of the simulacrum to be created (minimum 2,000 experience points).