"Are you pondering what I'm pondering Pinky?"
"Wuhhh... I think so, Brain, but if a ham can operate a radio, why can't a pig set a VCR?"
I am not sure under which conditions you can draw one. The rules say that it is once per game as a spoils effect. Does that mean that when you kill a monster, and there is a spoils effect, you can take a familiar instead of the printed spoils effect? Does it mean that when you kill a monster, you can take a familiar wether or not there is a printed spoils effect present? Perhaps none of the above?
Any time you kill a monster (once and only once per game) you may take a familiar.