Inaccurate?

Armor of Scales

( Dragon Magic, p. 15)

[Ceremony]

You imbue a target with the protection of a dragon's hide.

Prerequisite

Knowledge (religion) 4 ranks, Dragonblood subtype,

Benefit

You gain access to ceremonies based on your ranks in Knowledge (religion). Each ceremony provides up to four participants with a minor natural armor bonus. The ceremony takes 30 minutes and requires you to mark defensive runes upon the arms and torso of each participant with ash from a burned wooden shield of particular quality (see below). The effect of each ceremony lasts for 24 hours.

The natural armor bonus gained from this ceremony feat doesn't stack with a creature's existing natural armor bonus; use only the higher value.

Wyrmling Scales (4 ranks): Each participant gains a +1 natural armor bonus. This ceremony requires the ashes from a wooden shield of any size.

Adult Scales (12 ranks): Each participant gains a +2 natural armor bonus. This ceremony requires the ashes from a masterwork wooden shield of any size.

Wyrm Scales (18 ranks): Each participant gains a +3 natural armor bonus. This ceremony requires the ashes from a +1 (or higher) wooden shield of any size.