Toughen Construct

Transmutation
Level: Artificer 2
Components: V, S
Casting Time: 1 standard action
Range: Touch
Target: Construct touched
Duration: 10 min./level
Saving Throw: None
Spell Resistance: Yes (harmless)

Toughen construct thickens the unliving matter that forms a construct’s skin. The effect grants a +2 enhancement bonus to the creature’s existing natural armor bonus. This enhancement bonus increases by 1 for every three caster levels above 3rd, to a maximum of +5 at caster level 12th.

The enhancement bonus provided by toughen construct stacks with the target’s natural armor bonus, but not with other enhancement bonuses to natural armor. A creature without natural armor has an effective natural armor bonus of +0.