Cast Angel's Grace by paying ({W} magic symbol) , preventing you from losing the game this turn.
Cast Ad Nauseam by paying ({3} magic symbol) ({B} magic symbol) ({B} magic symbol) .
Resolve Ad Nauseam, revealing the top card of your library, putting that card into your hand and losing life equal to that card's mana value.
Repeat the process in step 3 until you revealed Sicken Dreams and cards in your hand are greater than opponent life total.
Cast Sickening Dreams by paying ({1} magic symbol) ({B} magic symbol) and discarding cards equal to amount of opponent life total, dealing damage to each creature and each players.