Would have to use the aberration type as opposed to vermin as it was very intelligent. Would have hunter (not webspinner) spider abilities as well.
Large Aberration
Poison (Ex): IT has a poisonous bite (DC xx, 1d6 Str initial and secondary damage).
Web (Ex): IT often waits in its webs, then lower itself silently on silk strands and leaps onto prey passing beneath. A single strand is strong enough to support IT the spider and one creature of the same size.
Approaching creatures of IT's web must succeed on a DC 20 Spot check to notice a web; otherwise they stumble into it and become trapped. Attempts to escape or burst the webbing gain a +5 bonus if the trapped creature has something to walk on or grab while pulling free. Each 5-foot section has 12 hit points, and sheet webs have damage reduction 5/—. IT can move across its own web at its climb speed and can pinpoint the location of any creature touching its web. An entangled creature can escape with a successful Escape Artist check (DC xx) or burst it with a Strength check (DC xx). Both are standard actions. The check DCs are Constitution-based, and the Strength check DC includes a +4 racial bonus.
Tremorsense (Ex): IT can detect and pinpoint any creature or object within 60 feet in contact with the ground, or within any range in contact with the spider’s webs.
Skills: IT has a +4 racial bonus on Hide and Spot checks, +10 racial bonus on Jump checks, and a +8 racial bonus on Climb checks. IT can always choose to take 10 on Climb checks, even if rushed or threatened. IT can use either their Strength or Dexterity modifier for Climb checks, whichever is higher.