text: Gideon Jura’s first ability doesn’t lock in what it applies to. That’s because the effect states a true thing about a set of creatures, but doesn’t actually change the characteristics of those creatures. As a result, whatever creatures the targeted opponent controls during the declare attackers step of their next turn must attack Gideon Jura if able. This includes creatures that come under that player’s control after the ability has resolved and creatures that have lost all abilities.