Arachnus Web is a common Enchantment — Aura card from Magic 2012 (M12), collector number 163. Current market price: $0.07 (foil $0.25), TCGplayer market prices via Scryfall.
Enchant creature Enchanted creature can't attack or block, and its activated abilities can't be activated. At the beginning of the end step, if enchanted creature's power is 4 or greater, destroy this Aura.