For example, if Clive's Hideaway's hideaway ability is copied and two cards are exiled, you may cast both exiled cards without paying their mana costs (assuming you control four or more legendary creatures at that time.) Gogo's ability can copy any activated or triggered ability on the stack, not just one with targets
Ward: Opponents can challenge this card, but cant choose it when resolving an effect
20 Years Of Magic: The Gathering, A Game That Changed The World , archived from the original on May 22, 2014, retrieved August 11, 2013 "Making Magic, Stages of Design"
those are: By the way, there are a few equipment cards with abilities when they become unattached or unattach as part of the cost: Bear in mind that, in some of these cases, unattaching can prove very harmful for the unequipped creatures
The Giant Games are here
June's Create-a-Card Competition: Fully-Evolved Basics