Terithran

Terithran are ugly, hairless humanoids, short and thin-limbed, with oversized ears. Some travelers joke that those ears are how they sense magic. They speak by telepathy.

Despite its frail look, an angered terithran rakes with two sharp claws each round for 1d8+1 apiece, and it uses its magical powers with real skill and tactics despite a modest intellect. It always detects magic, in fact unable to stop doing so. It also has four other powers that it can use a combined 16 times per day, including a blast of power.

On the Prime Material Plane it turns shadowy and less solid. Its AC improves to 3 and only silver or +1 or better weapons can harm it, but its movement drops to 15, it can use its special powers only 6 times a day in total, and its blast acts as power word, stun instead of dealing damage. For that reason most terithran haul victims home to the Ethereal before killing them, using their blasts to keep the wizard's allies away and relying on their natural magic resistance to get past the caster's defenses.

Each terithran sleeps alone in a tomb of solid ether at the heart of a winding, spiraling maze. To it, wizard magic is the worst evil there is: spells cast on the Prime Material Plane foul the part of the Ethereal they touch. Once sorcery grows strong enough to reach the Deep Ethereal, the creature rouses in fury, walks its maze, steps onto the Prime, and seizes the offender, often hauling him to the planes and demiplanes bordering the Ethereal for punishment, which means death. Rumor says it eats the wizard's heart, though whether as food or vengeance is unknown, since it does not otherwise seem to eat meat.

What wakes one is not entirely clear. It seems to respond to wizard spells of 7th level or higher, comparable effects from magic items, or a dense burst of wizard magic in a small area; one tale says about 16 spell levels cast round after round, all inside a 50-foot area, once roused a terithran. These are not firm rules: powerful magic is used constantly without waking them, and sages need more information before predicting their appearances.

Ethereal travelers have reason to worry too. Terithran ignore wizards on their own plane, but after dealing with a Prime offender one may stay awake and irritable for up to a week, waiting in its lair or wandering the Ethereal. The slightest offense provokes it, though a very gentle approach might earn some information, if it actually knows anything useful.

Terithran never interact with each other, not even to breed. No young have ever been seen, and nothing suggests they age or die naturally; they claim, and seem, to have always existed. Their lairs hold drained magic items, sometimes one with a little power left, along with wizards' bones. The strange multidimensional maze around the sleeping chamber is said to hold the secret of their plane-crossing, perhaps as a kind of planar path, but no one really knows.

Their origin is a puzzle. One story blames a long-gone god of the absence of magic for cursing them to resent its use. Another holds that they alone see the truth: that wizardry was introduced eons ago by an entropy-loving cabal to unmake the multiverse one spell at a time. A third says they guard their sleep because they are dreaming the multiverse, or another one, and enough spells will wake them and end it all. What is certain is that terithran barely fit into Ethereal ecology, producing nothing and consuming nothing. Mostly they sleep.