Originally Posted by
Beheld
The spell doesn't target one of all possible Efferti in existence, it goes out and finds a creature that can be called. If you call an Efferti, you don't play a game where you roll XdY to see which one of the infinity it targets, it just calls a valid target, since the planes are literally infinite and there are an infinite number of them, if you cast the spell it gets one of the ones that exists to be called. You might as well claim it calls a stone statute of an Efferti, or a pile of salt, or a corpse.