Monster: Dhees

Dhees, also known as "sniders", are horrendous creatures that skulk about the edges of the Zone. Giant serpents with four spider-like legs and a multitude of eyes, they seek large prey - horses, camels, and of course humans.

The dhees usually strikes from a cave or a burrow that it has dug, gaining momentum for its lunge by digging its spider legs into the terrain before surging forward.

It can of course be read like a book, and is said to contain knowledge about the Zone and its properties.

Snider art by Claudio Pozas, from here

Dhees

No. Enc.: 1

Move: 120' (slithering, plus generates momentum with spider legs)

AC: 5 (15)

HD: 8

Atk: 2d6 (talons) / 1d6 (fangs, poison) - both attacks are directed towards the same target

Morale: 9

XP: 920

Lunge: Can dig its spider legs into the surrounding terrain to speed its lunge forward. It will hold off attacking for a round to position itself carefully. The lunge is at a +3 to hit, but next round it is at -1 to hit and to AC as it's getting back into position.

Poison: If stung, save vs poison. Pass: take disadvantage on all actions for d6 rounds. Fail: Paralyzed for 1d8 turns. Onset time is 1-2 rounds in either case.

Motion Hunter: The snider relies on vibration and movement to track its prey. Characters may make Dex checks with disadvantage in order to freeze and not attract its attention. Loud bangs or vibrations have a chance of disorienting the creature.