Why do familiars not seem to have any resistance to power word kill? I've had my familiar killed at least 3 times by various necromancers with this spell on the first try, every time. Is this a game mechanic that I should just try and avoid or is there something I can do to prevent it, other than just not walking around with my familiar?

Edit:

Familiars also do not yell if they're hit with this spell in Town. Seems like they'd at least let out a death knell.