Consign to Memory is a key tool here. It counters colorless spells such as a cast Lotus Petal, though not the Petal's mana ability, since that isn't a spell. More relevantly, it counters triggered abilities, which can stop an Acererak attack trigger or the enter trigger of a permanent they put onto the battlefield with Show and Tell or Aluren, such as Atraxa's. Bilbo comes out because it doesn't interact with the core engine of Show and Tell and Aluren cheating big threats into play, and it is a low-impact body in this matchup. Brazen Borrower stays in. Its adventure can bounce Aluren or a resolved threat, but not Show and Tell, which is a sorcery and never a permanent. Snuff Out also stays, but be aware it can't target Atraxa or Acererak because both are black. The plan is to disrupt the combo pieces rather than race their finishers.