The Minotaur and It's Monster.
When you find yourself in a labyrinth, you will know that there is a minotaur long before you see it. No one enters a maze without expecting one. And when you see it, you will know it. Eight feet tall, with pale, mangy splotches of fur, twisting horns that are broken off to fit the narrow passages, milk-colored eyes that should not be able to see. This is the minotaur.
But it is not the monster. When you cut the brazen bull, no blood seeps out- only water and clay. When it retreats or evades, there is no trail to follow, save that left intentionally. Should you manage to kill the bull, it will melt into mud and pulp within the hour. Any adept wizard or burgeoning psionic will be able to tell you: this creature is a projection, a dream, an imaginary friend conjured into existence.
By whom?
Long years ago, a princess birthed a child. An illegitimate child. Sickly and sour, the child's visage was as disgraceful as its conception, and so the king had a room carved from the stones below his holdings. The child was left here to wither on its own, with no kinslaying needed or done by the king. The princess-mother used what little empathy she had for the spawn to leave it a toy, a small woodcarved bull to hold onto as it faded.
The child didn't fade. It only grew. And as it did, so too did the room and its walls. The child grew frail and blind, immobile and speechless in its prison that crept further into the stone each year. When the walls finally pierce into light, they remain open only a short period before sealing back up like a scab. Oftentimes, they close only once a handful of surfacefolk have wandered into the tunnels in search of treasure. They will find none. Only the Labyrinthian at the center.
The Minotaur
5HD, armor as leather. Attack as a battleaxe.
The Minotaur moves at 1.5 normal movement speed. It will never be lost within its maze.
The Minotaur can see in the dark, and is blinded for d4 minutes by bright light.
If slain, the Minotaur will be reborn in d6 hours.
Labyrinthian
0HD (1 HP), no armor. Defenseless.
The Labyrinthian is blind, deaf, and mute. It clutches its wooden bull, but does nothing else. It will die instantly if wounded.
When the Labyrinthian dies, the Minotaur will cease to exist, and a passage out of the Labyrinth will open itself up. The Labyrinthian's killer will dream of the life the creature could have had for the rest of their days.