You are free to use actual systems of magic for your fantasy, there's no obligation to do so. I'm not even sure how helpful it would be. It's not historical fiction.
You can base erotica on what people actually like to do, but fantasy and reality are quite often different. People read The Story of O without wanting to live it.
Last edited by QuantumIguana; 12-19-2012 at 11:26 PM.