Snow Spider, Small (CR 1/2)

Small Vermin
Alignment: Always neutral
Initiative: +4 (Dex); Senses: darkvision 60 ft., tremorsense 60 ft., and Spot +8

AC: 15 (+1 size, +4 Dex), touch 15, flat-footed 11
Hit Dice: 1d8 (4 hp)
Fort +2, Ref +4, Will +0
Speed: 30 ft., climb 30 ft.
Space: 5 ft./5 ft.
Base Attack +0; Grapple -6
Attack: Bite +5 melee
Full Attack: Bite +5 melee
Damage: Bite 1d4-2 plus poison
Special Attacks/Actions: Leap, poison
Abilities: Str 7, Dex 18, Con 11, Int -, Wis 10, Cha 2
Special Qualities: vermin traits
Feats: Spring Attack; Weapon Finesse
Skills: Climb +12, Hide +12~, Jump +24, and Spot +8
Advancement: -
Climate/Terrain: Cold marshes
Organization: Colony (2-5) or nest (6-11)
Treasure/Possessions: None

Source: Frostburn

Leap (Ex): Snow spiders are known for darting up to bite their prey, and instantly leaping back to avoid a return attack. They gain Spring Attack as a bonus feat. In addition, if a snow spider can jump on its prey (usually by making a Jump check as part of its movement), it can make a charge attack with a +4 attack bonus instead of the normal +2.

Poison (Ex): A snow spider has a poisonous bite.: DC 10, 1d3 Dex/ paralysis

The save DC is Constitution-based.

Tremorsense (Ex): A snow spider can automatically sense the location of anything within 60 feet that is in contact with the ground (or ice or snow on top of the ground).

Skills: Snow spiders have a +4 racial bonus on Hide checks, a +20 racial bonus on Jump checks, a +8 racial bonus on Spot checks, and a +8 racial bonus on Climb checks. Snow spiders use their Dexterity modifier instead of their Strength modifier for Climb and Jump checks. Snow spiders can always choose to take 10 on Climb checks, even if rushed or threatened.

*In snowy or icy environments, a snow spider's bonus on Hide checks improves to +8.

Snow spiders are hunting spiders, not web spinners, so they almost always attack from ambush, striking quickly and then dragging their prey into a tunnel or snow bank.

Snow spiders are aggressive hunting spiders that roam the tundra, bogs, and everfrost of cold regions. They paralyze their prey for later consumption.