Chapotraphouse

All magic in Game of Thrones are forms of blood magic. It isn't common because there is often a very high cost to pay and a strict taboo against even attempting it. Look at what happened to Dany when she attempted to use blood magic to exchange a horse for Drogo's life. The horse died, her unborn baby was sacrificed too without her knowledge and Drogo lived on in a comatose state.

Then Dany did blood magic in the other direction, burning Drogo, the Witch and her miscarried child in exchange for hatching the three eggs.

Lighting the glass candles? Requires blood. Offerings to the Old Gods at the Weirwood Trees? Human sacrifices and babies. Don't get me started on how many drowned victims had to be sacrificed to create the magic that saved Patchface's life via the merfolk. Shit is inherently evil. Magic in Game of Thrones is not a neutral act, and those who practice it openly are often feared and attacked.