Enchanted creature can't attack or block, and its activated abilities can't be activated.
When enchanted creature becomes the target of a spell or ability, destroy Ice Cage.
10/1/2009 If the enchanted creature becomes the target of a spell or ability, Ice Cage’s ability triggers and is put on the stack on top of that spell or ability. Ice Cage’s ability will resolve (causing Ice Cage to be destroyed) first.
6/8/2016 Activated abilities contain a colon. They’re generally written “[Cost]: [Effect].” Some keywords are activated abilities and will have colons in their reminder text.