The Idea: A casting Class that does not rely on a mental attribute.
The Flavor: You made a deal with the devil so to say and use your own life’s energy to fuel your spellcasting. You don’t need to be bright or wise or charming to use spells. Actually that is usually preferred by the beings that offer these things.
There are 3 types of pacts (one for each physical ability score):
Blood Pact: Casting stat = Constitution
Usually old and powerful Vampires offer these (or other powerful creatures that have to do with blood). You draw your spell prowess from your own blood (and therefore your Con Score).
Payment for these abilities includes being a food/blood source for the creature at the very least, but usually you have to do much more.
Skin Pact: Casting stat = Strength
Practitioners of this simple and brutal type of magic have huge, unnaturally swollen muscles. Their skin is stretched in such a way that it can rip open if strained.
For a Skin Caster their muscles turn into batteries that store their magic. The more magic is stored the more swollen the muscles are and the muscles visibly deflate with repeated usage of magic.
Gods/powerful beings that favor fighting can offer these kinds of pacts.
Bone Pact: Casting stat = Dexterity
This tricky type of casting only requires hand movements. While normal casters often need elaborate gestures to complete their spells, a bone caster takes it to the extreme. In a very lengthy (and painful) ritual runes are etched onto the bones in their hands and fingers.
These runes allow them weave magic by simply moving the hands in the appropriate patterns trained for hours and hours on end.
Certain rogue guilds offer these kinds of services. Or a magic academy that finds itself short on suitable students might pick the practice up to fill their ranks.
The Pact Caster:
General Stats:
Medium Base Attack
d8 Hitdie
2+Int Skillpoints
1 good save (Fortitude for Skin and Blood, Reflex for Bones)
General Class Skills: Knowledge(Arcana), Knowledge(Religion), Craft, Spellcraft, Use Magic Device, Profession
Blood Caster: Heal, Knowledge(Nobility), Disguise, Bluff, Diplomacy, Appraise
Skin Caster: Swim, Climb, Survival, Fly, Intimidate, Survival
Bone Caster: Stealth, Disguise, Perception, Bluff, Acrobatics, Escape Artist
Spellcasting:
All pact casters are spontaneous casters. They have an amount of known spells like a Sorcerer.
Due to their difficult approach to magic pact casters are very limited in their directly usable spell power. They only have 1 spell slot per spell level and can only gain more by having a high ability score. However when they have cast all their spells they can still continue casting albeit at a high price.
They start with a first level spell slot and gain a new spell-level at every uneven level to a maximum of 9. Pact casters have no cantrips (if they learn a cantrip they cast it as first level spell).
Pact casters can choose spells from any spell list (the GM still can put restrictions on the available spells depending on who they have a pact with. A Balor surely won’t offer “Holy Word” for example).
They don’t distinguish between arcane or divine spells. If it is important for an effect then treat the spells of blood and skin casters as divine and spells of bone casters as arcane spells.
Visuals:
Since pact casting is directly tied to the body its effects are hard to hide. It usually has a very noticeable effect on the caster.
As mentioned skin casters appear obscenely buff when full of magic and look like a wrinkly old person when empty.
Blood casters have a very rosy skin color when full with magic and turn pale and sickly as they use up their magic.
Bone casters have glowing runes on their hands and prolonged casting can result in them looking more and more like bone.
The Blood Pact:
Special Ability:
Blood regenerates very fast. Con damage is healed as 1 per hour (If she has plenty to eat. When starving, the regeneration is like that of a normal member of that race). Con drain heals 1 per day.
Overexertion Consequences:
To cast spells after all spell slots of a level are used up, a blood caster must add his blood as material component to his spells. Depending who they have a pact with that can mean cutting a wound into one’s body and spill the blood or it can by mysteriously drained from the body. However it is achieved, adding blood to a spell is part of the spellcasting and does not use up an action.
Adding blood to a spell causes Con damage. 1 point of Con damage fuels one spell level. You do not lose the ability to cast spells through this type of damage even if you sink below the usual required threshold. However the DC to resist your spells is reduced accordingly with your score.
If the accumulated Con damage is higher or equal to half your caster level (minimum 1, rounded down), then all the following Con damage is turned into Con drain. This drain can only be healed by natural regeneration (1 per day) and is not curable with magic. Proper treatment (DC 15 heal check) and plenty of rest can double the regeneration.
Temporal bonuses to Con (like from a barbarian’s rage) do not give you extra spells, but they do increase the DC.
Advantages: No restrictions on spell selection (except RP wise by GM)
Disadvantages: Casting is tied to your Con score. Overexertion reduces this score. Con is very important.
Skin Pact:
Special Ability: Strength Surge (works like “Might of the Gods” from the strength domain). Non-lethal damage is regenerated twice as fast.
Overexertion Consequences:
Spells cast over the limit put serious strain on the muscles (in extreme cases causing the skin to burst open). Every spell deals 2 points of non-lethal damage per spell-level to you (If you are immune to non-lethal damage this damage you can’t become a skin caster).
If you have accumulated non-lethal damage equal to twice your caster level, then all excess damage is lethal damage.
Advantages: Easy handling of the overexertion (It can simply be healed away).
Disadvantages: Skin casting lacks finesse and is the most primitive form of the three types. Spell selection is limited to the following spells.
Can only learn spells with a casting time of 1 standard action (Feather Fall is too short; Enlarge Person and Symbol of Sleep are too long for example.)
Skin Casters can only learn and use these three metamagic feats: Empower, Widen, and Maximize (but applying those does not increase the casting time)
Bone Pact:
Special Ability: Your hands are like scissors for the fabric of magic. This allows you to deflect magical attacks (magic attacks that require a touch attack to hit) with your hands like a monk can deflect arrows. [Optional: Also you qualify for the snatch arrows feat, which allows you to throw the attack back at the caster or keep it like a charge in your hand.]
Overexertion Consequences:
Execution for the spell weaving must be flawless for the spells to work without side effects. But little errors are unavoidable. They are compensated by the runes, but manifest as some kind of paralysis of the fingers and later the whole body.
For every spell cast over the limit you take 1 point of Dex damage per spell level. This is physically represented by a slow petrification-like process but otherwise follows the same rules as the effect on Con for skin casters. If you reduce your Dex score to 0 with this ability you turn completely into a statue made of bone and must be returned to life with a Stone to Flesh spell.
The Dex damage and drain can be healed by magic normally.
Advantages: Does not need words to cast. All spells are silent.
Disadvantages: Always needs both hands free to cast. Even a strapped on buckler is too much of a burden.