Sneak and Show is a glass-cannon combo deck racing to land Griselbrand, Atraxa, or Emrakul via Show and Tell or Sneak Attack, so this matchup is almost entirely about who assembles their plan first. The extra Unmask lets you strip their Show and Tell, Sneak Attack, or Force of Will before they can deploy it, which is especially valuable since you have very limited ways to interact with a resolved giant creature. Silent Gravestone comes in as cheap artifacts that don't slow your clock much, while trimming Poxwalkers (a mediocre blocker against a 7/7+ threat) and some looting lets you prioritize proactive discard and speed over grinding value.