Tattoos as a Magical Item

The denizens of the criminal underworld, phantasmagorical cults, ancient orders of fallen knights and shamans both wise and treacherous know that there is power in marking the flesh, that the life-force of the marked twists and fuels strange magic, while sigils of arcane power warp and empower the flesh they mark.

Classic American Tattoo

Magical tattooing is a potent form of sorcery that relies on the permanent linkage between the life energies of the marked individual and simple magical formula to create lasting magical effects without overly complicated arcane knowledge.  Generally such tattoos will be protective in nature, and almost all will effect only the tattooed individual as they are linked to his or her personal being.  Another common form of magical tattooing, is that of certain wizards (often deemed barbarous or simple by more academically inclined thaumaturges) who will tattoo themselves with their spellbooks.  This has the advantage of making it very hard to deprive the sorcerer of his store of mystical knowledge and provides a clear warning to other practitioners of how advanced a specific caster's knowledge is.  The tanned and preserved skins of great warlocks are a valuable magical commodity amongst sorcerers of this kind for the knowledge they contain, and it is not unheard of for casters to seek the skins of their enemies as trophies and to craft into magical garments.  Red Balthazzar, a puissant lich of the horse tribes was also known as Balthazzar the Skinner or Nine-Skin Red due to the large number of potent shamans he slew and flayed for their knowledge.

The primary limitation on magical tattooing is one of space, there are only so many suitable spaces on the body for magical tattoos, especially as they may not be covered by metal armor in order to be effective.   For each "level" of a tattoo it requires 1 space (as described below), with a level being either a measure of the warding tattoo's power or a spell level of a spell tattoo.  The inscribed individual is thus limited not only by space, but by the small number of areas for potent tattoos.

It is difficult to obtain magical tattoos, as very few of the magical practitioners that know the art are willing to work on outsiders, and one must typically be a member of some sort of secret society or tribe that knows the secret of specific tattoos. For example: An Assassin cult might know tattoos that render their wearer hard to spot (A natural stealth skill of 3), provide protection from poison or give them infravision, but is unlikely to know tattoo that strengthens its wearer.  A tribal war shaman may know tattoos that strengthen his tribes warriors, and even make them immune to blades, but won't know tattoos that protect against poison.  The similarity of between these groups is that the both are likely to refuse to tattoo outsiders.

Locations and Space for Magical Tattooing
Spaces in capital letters are regions that any one spell must contain.  The sub regions are each limited to a single ward or spell up to the level listed.  Thus a magician could place either a single spell of up to a fifth level spell on his right arm, 4 first level spells, or 3 first level and 1 seconf level spell level.

HEAD/NECK - (2 levels total) 1 face/1 neck
RIGHT ARM -  (5 levels total) 1 shoulder/1 upper arm/2 lower arm/1 hand
LEFT ARM - (5 levels total) 1 shoulder/1 upper arm/2 lower arm/1 hand
FRONT TORSO - (8 levels total)  2 Left Pectoral/2Right Pectoral/3 Stomach/1 groin
BACK TORSO - (10 levels total)
LEFT LEG - (6 levels total) 1 foot/2 calf/3 thigh
RIGHT LEG - (6 levels total) 1 foot/2 calf/3 thigh

Advantage of Tattooed Spellbooks.

In addition to the practical matter of making a spellbook harder to steal or take away there are very real magical advantages to inscribing oneself with ones magical formula.Magical Spell tattoos may be read as scrolls by those they mark (or by those who carry the inscribed skin of another).  Doing so will of course erase the spell, as with a regular scroll - but not always.  The link between the life of the caster and the magical writing allows the retention of the spell tattoo much of the time.  On a use of a tattooed spell as a scroll the caster may role a save vs. spells to retain it with the following formula:

 D20 > (Save vs. Spells + level of the tattooed spell, -- level of the caster, - Con Bonus of Caster)

There are two major side effects to this means of casting: destruction of the spell tattoo and injury to the caster.  Destruction of the Spell will mean that it is not simply erased, but burns, sloughs off or boils its way through the flesh creating a mass of scars that cannot be tattooed on again, without the use of powerful regenerative magic or abilities.  When a wizard attempt to retain a tattooed spell after using it as a scroll, regardless of success, he will suffer injury and exhausting equal to 1D2 HP x level of the spell as his lifeforce is used to restrain the spell's collapse into entropy. 

Warding Tattoos
The most common magical tattoos are for the purpose of protection or warding, most protective magical effects can be replicated in this form as can bonuses to certain skills or abilities.  The more powerful tattoo the larger it will be.  One limitation on protective tattoos is that only one tattoo of a specific type will effect a marked individual, thus the effects of multiple protection tattoos would not be cumulative.

Examples:  
Tattoo of Protection from Charm, +1 Save vs. Charm - 1,000 GP (Lvl 1)
Tattoo of Slow Posion, (as spell, always effective) - 1,500 GP (Lvl 1)
Tattoo of Spell Protection, +1 Save vs. Spells - 1,500GP (Lvl 1)
Tattoo of Strength, +1 STR - 2,500GP (Lvl 2)
Tattoo of Protection, -1 AC - 3,000GP (Lvl 2)
Tattoo of Fury, bare handed attacks as magical weapon - 2,500 GP (Lvl 2)
Tattoo of Cold Blood, Fire Resistant - 3,000GP (Lvl 2)
Tattoo of Force, +1 Hit/+1 Damage - 5,500 GP (Lvl 3)
Tattoo of Protection from Evil, As Spell - 7,000 GP (Lvl 3)
Tattoo of Regeneration, +1 HP per round - 25,000 GP (Lvl 6)
Tattoo of Beguilement, Charm Person once per day - 30,000 GP (Lvl 6)
Tattoo of Protection from Cold, Immune to Cold - 70,000 GP (Lvl 7)
Tattoo of Missile Turning, Immune to Normal Missiles - 80,000 GP (Lvl 7)
Tattoo of Invulnerability, Immune to Normal Weapons - 120,000 GP (Lvl 9)

Single Use Tattoos:
 More powerful individual spells may be tattooed onto non-magic users, but must be excised by their owner (destroying the skin of the area, and rendering it unavailable for future tattooing unless a regeneration spell or similar means of healing is used).  Each of these spells covers only a single space, regardless of power.

Examples:
Gaseous Form (as potion) - 8,000 GP
Burning Hands (as spell) - 500 GP
Polymorph self (as spell) - 8,000 GP