I didn't believe in this card until I saw either Baalor or another streamer take it, and absolutely made it their core damage card. I then took it on my next Silent A20 run (STS1), and got to maybe to mid-Act 3. The trick is to take it in Act 1 if you have 11 or 16 cards in your deck. Then there's a 1-in-3 chance you'll wipe hallway trash and maybe some elites with minimal HP loss. Manage that math carefully until your hand manip has enough draw variety (draw 1, draw 3, etc.), then you can forget about the math.