There was this image on Insiider by Shreve that never got made into a card, so it got incorporated into this card.  It's a hyren, and the Cald theme for this expansion are Volcanic creatures, so it got that tag as well.  The Furnace name also feeds off the Heart of the Furnace theme that runs through Cald in this expansion as well.  This is basically another anti-Nar card, and it makes short work of Arctic cards as well.