Notable appearance: Gotham City Sirens #24
Sometimes Batman leaves the cave with a choice of weapon specific for the villain he knows he is about to face. And whenever he crosses paths with the monstrous Clayface, he usually makes sure he brings along his special heated Batarangs. This gadget has a built-in device that causes it to heat up to near-volcanic temperatures when deployed.
When used on Clayface, this Batarang heats up his muddy hide and instantly dries it out—causing him to crumble to the ground. Obviously this tool can be used on other foes than just Clayface. Batman has used variations of this same idea on Mr. Freeze and his frozen victims throughout the years as well.