Magic Elementals

The rarest of elementals, magic elementals are only born when already powerful spirits use the essence of magic itself to create their body. They are immensely powerful entities, although they suffer from the same drawback as other elementals. Since the larger an elemental is, the closer it must remain to its element, magic elementals are typically unable to leave extremely magic-rich places such as the fairy kingdom, and most forms of anti-magic are absolutely crippling to them. They may subsist on magic of the environment, or take the form of something fit for hunting. Because their body is defined by their whims, their behavior can become erratic and unpredictable. Unluckily for magic users, magic elementals have the most heightened awareness for the predator sense, and can likely pinpoint them miles away, just as if the spell caster was next to them. However, since they are such an immense focus of magical energy, they in turn can be sensed by anything capable of the sense from great distances. If you've sensed it first, it's smartest to activate something with anti-magic capabilities as self-protection or, better yet, leave the area. Magic elementals are the natural predator of genies, seeing the extremely magic-rich beings as 'candies in a jar'.

===Floating Heads===
One of the most disturbing types of elemental known to exist, floating heads spend most of their existence as a diffuse, slumbering presence underground. They don't take a form, much less notice of their surroundings, until high concentration of magic disturbs their sleep. The use of magic around a floating head during its slumber causes it to gradually awaken, starting to feed off the magic as it is gathered. They don't take much at first, allowing for magic to function normally, but they quickly get greedy enough for wizards to notice. A wizard headstrong (or desperate) enough to continue using such will find themselves in a very dire predicament as one of their spells eventually outright fizzles and the floating head manifests its form instead!

A manifest floating head looks like a comely female- with no body below the neck, her head enshrouded in a morass of ethereal, shimmering tendrils, much like ghostly hair. The head itself measures around eighteen feet tall, more than enough to swallow a human whole. They are heavily decorated with collars, earrings, crowns, face-paint and headgear, sometimes even with facial piercings, eyewear or masks; while these objects may look like stone, metal, bone, coral, plastic, leather, jewelry, live flesh or what have you, they're actually part of the floating head, and fade away if somehow removed. The designs they sport veer towards the complicated and intimidatingly bizarre, sometimes including such features as moving pieces, musical instruments, "slots" within the face, and even body parts. It is theorized that floating heads are capable of changing those designs, but the lack of brave souls willing to look at one twice has prevented this from being confirmed.

Floating heads usually devour the wizard that "summons" them right away, rarely being persuaded to chat instead; a floating head will fade back into slumber less than a minute after appearing unless they eat, and this knowledge makes them tend to be rather inflexible on that respect. They become chattier after eating, hoping to fill the borrowed time with something, but their voracity inevitably comes up every few minutes. Those who have chatted with one know them to be frightfully intelligent, and rather fond of news about the world, which they claim to mull over between enforced periods of inactivity: having interesting tidbits may save your life with them.

Being made of magic makes them less than material; these elementals are perfectly capable of floating through solid objects, a great advantage in the underground they prefer to inhabit. They can disrupt spells around them with a mere glance; only weapons that harm ghosts are practical to use on them, as spells won't work without their consent. They prefer to snack on other magical beings if available, much like other magic elementals.

* Credits to Fish and Silent-eric for the description of magic elementals and to Stabs for the Floating heads.