Ruby Storm is a pure combo deck looking to chain rituals like Desperate Ritual and Pyretic Ritual into a Grapeshot or Past in Flames kill, so Thoughtseize is our best tool to proactively strip their key combo piece or Ral, Monsoon Mage before they can go off. We have essentially no other way to interact with their spell chain once it starts, so maximizing hand disruption and mulliganing aggressively for Thoughtseize is the plan. We cut slower value cards like Formidable Speaker, Dredger's Insight, and Strangleroot Geist since they do nothing to stop the combo and we need to be as disruptive and fast as possible. Walking Ballista remains useful as a way to close the game quickly before they assemble their kill.