Fire giants make for excellent mid- to high-level threats. Where else are you likely to find a lair where hell hounds come standard, with the optional red dragon or pyrohydra upgrade (not to mention the troll and ettin servant package)? And Paizo’s fire giants are as likely to be hanging out in the desert or underground as in some Viking landscape. They’re also militaristic, so it’s easy to imagine them in adventures typically sized for hobgoblins or Wizards of the Coast’s githyanki. In fact, there’s no reason they can’t be the big bad guys in an entire campaign arc. After all, in the closing act of the Ragnarök, it’s no god who sets the world on fire—it’s a fire giant…
The mark of a truly cosmopolitan city is one where giants mingle as easily as people. Surt the Smith is a fire giant who has lived in Greater Elb for years. He is also a sleeper agent for the General’s Embers, a fire giant military fraternity. When three vargouilles fly into his forge and burst into flames, he trades his aprons for armor and attempts to kill Greater Elb’s half-elven High Council that very night.
Fire giants rule an empire to the south, following the deserts and mountains across half a subcontinent and ruling over humans, dwarves, azers, ettins, trolls, and olive treants alike. Now they begin to menace the coastal cities with copper and steel war machines. A party of adventurers is sent to take out fire giant high sultan. But first, they must find the lair of some unlikely allies: the mountain fortress of the tengu hashashin.
The planar realm of Jotunlandt’s fire giants are training for a war—a war that will reclaim reality for giantkind or burn it to cinders. Their leader is an animated decapitated head of a titan that dwells in the hot springs at the base of Jotunlandt’s highest peak (a peak so high it pierces the Rook of the Rocs, a mythical aerie). When not directing the fire giants, the titan head will answer three questions any humanoid puts to it. It is compelled to do this by the same geas that keeps it animated…but it is not required to keep its fire giant thralls from harming any and all humanoids impertinent enough to try.
—Pathfinder Bestiary 124–125