The first step in the sacrificial process is finding or building an appropriate place, be it an altar, a carefully selected grove, or whatever else seems appropriate. Knowing how to prepare a location requires at least five ranks of Knowledge (arcana). The cost for preparing a location is (I figure somewhere around 100 gp per highest spell level you plan on using the area for, but I need a dollar equivalent, and a Wealth Check DC). Preparing the area takes 3d4 days, and requires a Knowledge (arcana) check versus a DC of 15.
The sacrificial victim must be helpless. Normally, he will be bound, drugged, unconscious, crippled, or affected by some similar condition. The sacrificial process is a modified coup de grace. This CDG requires two full rounds, but the caster inflicts the maximum damage with his attack. If the victim dies, the caster can tap the victim’s ability scores, but only in the next round. The percentage of the ability scores the caster can tap is based on the awareness of the victim.
If the creature is intelligent and conscious, such as a human virgin or something classic like that, then the caster can tap all of the victim’s ability scores. If the victim is unintelligent, such as a cat or rabbit, or intelligent but unaware of what is occurring, such as a drugged elf, then the best the caster can do is tap up to one-half of the victim’s ability scores, rounded down. There is a spell available that allows a character to tap the full ability score of an unintelligent or unaware creature.
The caster must cast his desired spell on the round following the sacrifice. During this round, any spell he casts will inflict ability damage to the victim’s ability scores instead of the caster’s. If he waits and this crucial round passes, then he loses access to the victim’s scores.
For example, Joe has plans to cast magic jar, a fifth level necromancy spell. Casting this would normally cost him 1d8 Constitution, but he doesn’t want to spare those points, so he decides to sacrifice a local common girl to power his spell. He has eight ranks in Knowledge (arcana), so he is able to prepare the location, a special stone alter. He spends nine days preparing the altar to receive sacrifices and rolls a 20 on the Knowledge (arcana) check. Through duplicitous means, Joe manages to capture a local barmaid. He securely binds her to his altar, and makes sure all of the other components for his spell are prepared.
Things are as they should be, so Joe makes sure his victim is awake and grabs his large dagger (effectively a short sword, 1d6 damage, x2 critical). As he begins to mumble the words to his spell, he plunges the dagger into his victim’s chest, inflicting the maximum damage (12 points). The victim survives the damage barely, but fails her Fortitude save versus a DC of (10 + 12) 22, and dies. On the next round, Joe casts his magic jar spell. Joe’s victim had a Constitution of 10, and he scores a seven on his 1d8 roll. Since his victim was intelligent and aware, her 10 Constitution absorbs all of the ability damage inflicted by Joe’s spell, saving Joe from temporarily losing seven points of Constitution.
Now, had Joe’s sacrificial victim been small dog, he would have been able to tap only one-half of the dog’s (let's say) 10 Constitution, so he still would have lost two points of Constitution temporarily.
