Spin Web is a monster skill used by the Giant Spider class monsters. When near death, they will run away from the player while spraying globs of spider silk behind them. These form into small trails of webbing that greatly slow you while walking over them, making it hard to catch up to the fleeing spider.
If you can be delayed long enough for the spider to heal, it will come back and rejoin the fight.
Damaging Skills
Fire — Fire Arrow • Fireball • Fire Bolt • Fire Hit • Firestorm • Fire Wall • Flame Circle • Hydra • Incineration Nova • Inferno • Meteor
Ice — Arctic Blast • Blizzard • Cold Touch • Fire Hit (Cold) • Freezing Charge • Glacial Spike • Hoarfrost
Poison — Poison Bolt • Poison Breath • Poison Cloud • Poison Spit • Poison Spray • Poison Sting • Poison Strike
Lightning — Lightning • Lightning Arrow • Lightning Globe • Red Lightning Hose • Shocking Hit • Spark Defense
Physical — Blow Dart • Charge • Corpse Cannon • Destructive Strike • Ground Tentacle • Leap • Leech-life Ball • Quill Dart • Slam
Magic — Bone Spirit • Hellish Projectile • Unholy Bolt
Non-damaging Skills
Indirect Attack — Blood Mana • Curses • Mana Rift • Minion Frenzy • Putrify • Spin Web • Stun
Spawning — Bone Prison • Festering Appendages • Lay Egg • Revive • Summon Minion
Self-effect — Bone Armor • Burrow • Fly • Frenzy • Heal • Teleport • Vile Effigy