My Big Game Hunter characters have had Butchery trigger with non-animal monsters (would you eat meat you got from a mummy? And how do you get meat from an AI at all?!) and with monsters that are still alive. Since this doesn't fit the logical way it's supposed to work, I present it as a bug.
Last skill shall carve the flesh off your enemies, or it shall give them flesh to carve it from. In other words replace blood with flesh in the description and it still doesn't make sense but you get the point.
