Mantic is an adjective describing anything related to fortune telling or divination, from the Greek mantis for profit. This is indeed where we get mantis, referring to an insect that holds its arms out like it's praying. For information on all things mantic, I read the essay Mantic Mania by Robert Devereux.
Extispicy was an ancient practice by which soothsayers sliced open a dead animal to read its guts, believing that in so doing, they could see the future. It was practiced by ancient Babylonians, Mesopotamians, Etruscans, and Romans.
Seriously? Who came up with this? And who the hell believed them? "Hey, I know, let's vivisect us some sheeps and then poke around in their livers and then we'll know the future." Wouldn't it be a lot more believable just to be like "Hey, I know the future," and not have to worry about all the guts and stuff? Because even if organs did tell the future, how the hell would you know how to interpret them? Did the god tell people? In that case, couldn't the gods just tell people the future? Maybe it was a ploy on the part of butchers to sell more entrails. Bill Brohaugh, author of Everything You Know about English is Wrong (hurtling through cyberspace into my Kindle as we speak) coined the term expository extispicy in this blog post, referring to people's practice of predicting a word or phrase history by cutting it up and trying to reverse engineer it. Like the myth I once heard that the expression "mind your own beeswax" comes from the fact that women used to use bees wax as some sort of foundation, and women would say that to each other when one woman was staring too hard. Speaking of wondering who thinks these things up and who believes them.
Anthropomancy is the art of divining the future by looking at human entrails. That one's pretty useful. "I predict this person will remain dead." You're right roughly 100% of the time.
Another way of divining the future? Poop. Scatomancy refers to reading a person's fortune by looking at their poo. I shit you not. (See what I did there?) I don't care what my sources say, that shit sounds made up. (See what I did there again?)
I guess, though, in a way, this is one method of divination that might stand a chance... I mean, if someone's poop has worms in it, say, you can predict they're going to have problems with worms. Or something.
Hospitals, I suppose, are practicing scatomancy when they demand a stool sample. On the obligatory musical episode of Scrubs, the song Everything Comes Down to Poo informed us that "the answer's not in your head my dear, it's in your butt."
Myomancy is the practice of predicting the future by watching the movements of mousies. My best friend practices myomancy - sometimes she gets to sit around all day watching mice run around in an enclosure, how far out into the open they run. How many poops they make. Someday, they hope, they'll be able to use myomancy to determine how the brain can better fight off diseases. Or something. To tell you the truth, when she talks about her job, I only understand about one in every five words. I'm flattered that she thinks I understand, though, and that's what counts.