I guess these occur more in fantasy novels. The genre my novel would fall into is probably 'fantasy and horror' or 'historical fantasy'. I've had to put a couple of ideograms in as small illustrations (think Wilbur Smith & Warlock, or Tolkein with Elvish script). It's not excessive, just two small pictures about 1cm x 1cm within 20,000 words. I'm not sure if this is OK. One is to depict a sigil and one is used to depict the 'imaginary/connecting' lines between a set of constellations. Just wondering what other peoples thoughts are on these? I know the obvious response is you should be able to describe it with words, but some things need to be really specific and accurate and they are hard to describe beyond tracing lines in the night sky.