Arachnus Web | Magic: The Gathering
Formats Arachnus Web is Legal in
Official Oracle Text for Arachnus Web
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 Arachnus Web.
Official Rulings for Arachnus Web
9/22/2011 : If the enchanted creature's power isn't 4 or greater when the end step begins, the last ability won't trigger at all.
9/22/2011 : If the ability triggers, but the enchanted creature's power is reduced to 3 or less before the ability resolves, the ability will have no effect. Arachnus Web won't be destroyed.
9/22/2011 : If Arachnus Web enters the battlefield attached to an attacking or blocking creature (due to Arachnus Spinner's ability, for example), that creature will continue to attack or block.
7/1/2013 : Activated abilities contain a colon. They're generally written "[Cost]: [Effect]." Some keywords are activated abilities; they have colons in their reminder text.