Encounters by Locale: Anauroch - The Sword - Mountains/Hills (Night)

Monstrous Spider, Small (CR 1/2)

Small Vermin
Alignment: Always Neutral
Initiative: +3 (Dex); Senses: darkvision 60 ft., tremorsense 60 ft., and Spot +4*

AC: 14 (+1 size, +3 Dex), touch 14, flat-footed 11
Hit Dice: 1d8 (4 hp)
Fort +2, Ref +3, Will +0
Speed: 30 ft., climb 20 ft.
Space: 5 ft./5 ft.
Base Attack +1; Grapple -6
Attack: Bite +4 melee
Full Attack: Bite +4 melee
Damage: Bite 1d4-2 and poison
Special Attacks: Poison, web
Abilities: Str 7, Dex 17, Con 10, Int -, Wis 10, Cha 2
Special Qualities: Vermin
Feats: Weapon Finesse (bite)
Skills: Climb +11, Hide +11*, Jump -2*, and Spot +4*
Advancement: -
Climate/Terrain: Temperate forest
Organization: Colony (2-5) or swarm (6-11)
Treasure: None

Source: Monster Manual

All monstrous spiders are aggressive predators.

Monstrous spiders come in two general types; hunters and web-spinners. Hunters rove about, while web spinners usually attempt to trap prey. Hunting spiders are speedier than their web-spinning counterparts and use higher speed numbers shown in parentheses.

Monstrous spiders of both types have roughly circular bodies surrounded by outspread legs: 3 feet wide* and 3 inches high.
*The number includes the spider's body and its legs; the actual body diameter is about a third of the total.

Faerûnian Random Encounters by Region and Locale