Sligh's clock is too fast to durdle against, so bring in cheap, efficient answers to their creatures. Swords to Plowshares is a one-mana answer to Ball Lightning, Grim Lavamancer, or Jackal Pup, and Thrashing Wumpus can repeatedly ping down their small X/1s and X/2s while you stabilize. Arcane Denial is a poor use of mana and card advantage against a deck that doesn't care about extra cards, and Infernal Contract's life loss is too risky against a burn-heavy plan. Focus on surviving to your storm turn rather than trading resources one-for-one.