Shadow Spider (CR 12)

Huge Magical Beast
Alignment: Always neutral
Initiative: +5 (+1 Dex, +4 Improved Initiative); Senses: darkvision 60 ft., low-light vision, Listen +5, and Spot +6

AC: 13 (-2 size, +1 Dex, +4 natural), touch 9, flat-footed 12
Hit Dice: 13d10+65 (136 hp); DR: 10/magic
Fort +13, Ref +11, Will +5
Speed: 50 ft., climb 30 ft.
Space: 15 ft./10 ft.
Base Attack +13; Grapple +17
Attack: 4 claws +19 melee and bite +17 melee
Full Attack: 4 claws +19 melee and bite +17 melee
Damage: 4 claws 2d4+8, bite 2d6+4 plus paralysis
Special Attacks/Actions: Improved grab, paralysis, silk slick
Abilities: Str 26, Dex 13, Con 20, Int 5, Wis 13, Cha 8
Special Qualities: shadow walk, SR 23
Feats: Improved Initiative; Improved Overrun; Lightning Reflexes; Multiattack; Power Attack
Skills: Climb +20, Hide -3*, Listen +5, and Spot +6
Advancement: 14-26 HD (Huge); 27-39 HD (Gargantuan)
Climate/Terrain: Any underground
Organization: Solitary
Treasure/Possessions: Standard

Source: Monster Manual II

Improved Grab (Ex): If a shadow spider hits an opponent that is at least one size category smaller than itself with two claw attacks, it deals normal damage and attempts to start a grapple as a free action without provoking an attack of opportunity (grapple bonus +29). If it gets a hold, it has the option to conduct the grapple normally, or simply use two claws to hold the opponent (-20 penalty on grapple check, but the shadow spider is not considered grappled). In either case, each successful grapple check it makes during successive rounds automatically deals damage fat two claw attacks.

Paralysis (Ex): A shadow spider's teeth are coated with a paralyzing fluid. Any creature hit by its bite must make a successful Fortitude save (DC 21) or be paralyzed for 4 rounds.

Silk Slick (Su): As a full-round action, a shadow spider can spray a layer of spider silk over any solid surface. It can cover up to 100 square feet with this substance, which dries and evaporates in 13 rounds. The slick silk functions in all other respects like a grease spell (caster level 13th; Reflex save DC 21).

Shadow Walk (Sp): At will, a shadow spider can use shadow walk (caster level 10th; Will save DC 16).

Skills: A shadow spider gets a +20 circumstance bonus on Hide checks when in shadows.

A shadow spider prepares elaborate traps for its victims in dungeons and caverns. It uses its silk slick ability to make a slope or stair slippery, then waits in the shadows at the bottom. When a creature falls, the shadow spider steps out of the shadows and attempts to grab its prey with its four foreclaws. If successful, the monster uses shadow walk to carry the victim to its larder in the Plane of Shadow. Once there, the shadow spider paralyzes and abandons that creature, then returns to its trap for more prey. Only when there are no more creatures, or it is in danger of dying, does a shadow spider return to its larder and begin eating. Shadow spiders never clean up their traps, so adventurers occasionally get forewarning of one from the dropped items (belongings of past victims) that litter the area.