Attempts to burst a web by those caught in it suffer a -4 penalty. Web spinners can create sheets of sticky webbing up to three times their size. They usually position these sheets to snare flying creatures but can also try to trap prey on the ground. Approaching creatures must succeed on a Perception check to notice a web; otherwise they stumble into it and become trapped as though by a successful web attack. 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. A creature can move across its own web at its climb speed and can pinpoint the location of any creature touching its web.