With Shields it's easy. Why? Because of when AI plays Miracle. You simply whittle them down with 10-20 attack per turn (depending on how bursty your deck is), then hit them for over 50 damage on the last turn when they have about 50 left.
I wouldn't recommend trying to deny
in most matches. Dims have always been more than enough to defend against Paradox and similar FG's, and Miracle is easily circumvented.
But yes, you need to draw Shields. Sometimes you don't. Happens with all Dim decks that have no draw power. I'd love SoBe's in that deck if I ever used it, actually.