Whenever a creature attacks you or a planeswalker you control, it gets +2/+0 until end of turn.
: Target player other than Crown of Doom's owner gains control of it. Activate this ability only during your turn.
11/7/2014 You are Crown of Doom’s owner if it started the game in your deck. Therefore, once you hand off the Crown, your opponents cannot give it back to you by activating its ability (although other effects, such as the one Zedruu the Greathearted’s ability creates, may do this).