Erhnam Djinn

Oracle Text

At the beginning of your upkeep, target non-Wall creature an opponent controls gains forestwalk until your next upkeep. (It can't be blocked as long as defending player controls a Forest.)

Card Rulings

10/4/2004 In multiplayer games you can choose a different player’s creature each upkeep. You are forced to pick a creature that some opponent controls if there is at least one creature on the battlefield that is a legal target.
10/4/2004 If you have more than one Djinn, you can have all of them target the same creature with their ability.
10/4/2004 If there are no creatures your opponent controls to target at the beginning of your upkeep, ignore this ability.