Equipped creature has fear. (It can't be blocked except by artifact creatures and/or black creatures.) Whenever equipped creature deals combat damage to a player, you may draw a card. Equip
Official Rulings for Mask of Riddles
5/1/2009 : If a Mask of Riddles you control somehow winds up equipping a creature you don't control, Mask of Riddles's triggered ability will still trigger whenever that creature deals combat damage to a player (even if that player is you). You will control that ability, so you may draw a card.