I swear I recently read in the RAW about a type of magic where you were able to sacrifice an animal, and then use it to to power magic items. But I can't seem to find it in the supplements.
Any help would be appreciated.
Thanks!
Hermetic sacrifice (the mysteries, revised p. 117) allows sacrificing animals to replace some of the vis needed to contact pagan deities, but not for enchanting. That is the only reference I am aware of that involves animal sacrifice.
The Verditius Major House Mystery Bind Magical Creatures (HoH:MC, page 134) sounds like what you're thinking of, but doesn't actually sacrifice the animals.
Spell Binding (TMRE, page 27) & Hermetic Empowerment (TMRE, page 64) are spirit based, but can also power spells and devices after a fashion.
A point to throw in here- animal sacrifice described in Hermetic sacrifice does indicate that it works if the entity is cooperative, so sacrificing animals to bind deities to your enchantments is a no go...
The Zoroastrans have at least one sacrifice
RoP:D 117 in the Saoshant's elixir,
of an animal with divine might.
Bob