text: Say you activate Gideon, Champion of Justice's second ability, and then an opponent gains control of him before combat. You may have any of your creatures attack Gideon, Champion of Justice (since he's still a planeswalker). Then Gideon, Champion of Justice may block (since he's a creature). He may block any eligible attacking creature, including one that's attacking him! During combat, he behaves as an attacked planeswalker and/or a blocking creature, as appropriate. For example, he deals combat damage to any creatures he's blocking, but he doesn't deal combat damage to any unblocked creatures that are attacking him.