Ruby Storm relies heavily on Past in Flames to flash back a graveyard full of rituals and cantrips, and Rest in Peace exiles that graveyard on entry and keeps it that way, completely cutting off their flashback plan and any Manamorphose or Wrenn's Resolve recursion. Pest Control also sweeps away Ruby Medallion before it can start discounting their red spells, which meaningfully slows their mana development. Teferi is weak here since it can't stop instant-speed storm turns and its -3 does nothing to a hand full of spells already cast, so it and some lands make way; prioritize deploying Rest in Peace as early as possible since a resolved Past in Flames or Hex Magic turn can end the game outright.