Mars' Ancile Buckler Shield

Greece:
The original shield that the nymph Egeria created 11 other copies from. When used, it protects the user from any and all damage from the direction the shield is pointed (e.g. if pointed to the front of the user, they can still be harmed from behind). Downside: User feels that they must sacrifice all quadrepedal animals, mostly pigs, rams, oxen, and a single horse, and eat them themselves. (This can cause disease if eaten raw or incorrectly cooked.)