While Maralen is on the battlefield, a player can’t choose to draw cards (or choose to have another player draw cards) as a spell or ability resolves. For example, if you cast the Development side of Research // Development (“Put a 3/1 red Elemental creature token onto the battlefield unless any opponent lets you draw a card. Repeat this process two more times.”), you’ll put three Elemental tokens onto the battlefield because your opponents can’t “let you draw a card.”