A. THE CAVE-MOUTH
You face the mouth of a cavern carpeted with incandescent and undulating cilia* whose appearance suggests something not quite plant or insect. The stalks shudder to the stuttering breezes that wrap around the entire isle like invisible, clutching fingers -- probing the pale, reeking mist that rises from the stagnant lake of gray ooze surrounding you. It clings to your body and smells strongly of ammonia and old metals baked in a smith's furnace.
The mouth of the cave is trapezoidal -- much wider at the top than the bottom. The walls pinch inward about ten feet in, and you will need to walk sideways to pass through the gap. Beyond this gap you can see a massive, mist-pocked boulder partly obscuring a dim corridor.
Above you hangs the undead wizard's fastness like the black mausoleum of an ancient king. It is windowless, featureless and not particularly vast, narrowing at the top to perhaps 50 ft. x 50 ft., though it is difficult to be certain from this vantage. The edifice appears to have burst upward from beneath the isle's crust fully realized, leaving bits of rubble and wiry vegetation scattered in its wake.
Everything beneath the fortress is composed of the same colorless marble-like strata. You note that the mist seems to have eaten worm-like holes into the exterior of this place, but beyond the gap you can see that the stone is smooth and glistening like uncurdled cream.
As you approach the entrance the cilia-stalks appear to become agitated and extrude further out of the stone. Each of their sinewy tips thrusts out a whip-like, double-forked tongue that methodically and cautiously tastes its way toward you. There are thousands of these tongues, and as they gather they begin to resemble a massive head of writhing hair or the unkempt beard of a particularly hirsute giant.
[The cilia is a harmless but difficult to damage collective organism (stalks are AC -2, HP 40, immune to non-/magical fire and cold attacks). Its purpose is to taste and analyze any creature passing through the cave's gap and telepathically send this information to Memnodoror. Please note that it is slightly and incurably senile and will fail to communicate with the wizard every 2-in-6 occasions something passes through it. Any violent response to its (mostly gentle) probings will cause the cilia anxiety and guarantee that the lich is alerted.]
*cilium (pl. cilia): a short, hairlike vibrating structure.