Can you define it, first?
I'm not sure whether you're asking if using the phrase "slain" is Biblical, or whether you're asking whether actually
being "slain" is Biblical...
And it might help to know what you mean by "slain" anyway... usually when I hear people use that phrase, it doesn't imply that they were unconscious, but that they fell to the floor under the power of the Holy Ghost (or that they fell out laughing).
