Jeskai Ephemerate is heavily blue, running Counterspell, Preordain, Lorien Revealed, Augur of Bolas, Murmuring Mystic, and Mulldrifter, so Red Elemental Blast and Pyroblast are excellent, countering key spells or destroying blue permanents like Murmuring Mystic or Archaeomancer. Guttersnipe is vulnerable to their removal suite (Skred can deal significant damage once they have snow permanents) and doesn't close games fast enough against their value engine, so trim a couple copies for more disruption. Sazacap's Brew and Highway Robbery are too slow against a deck that out-values you with Ephemerate loops and card draw, so prioritize efficient burn and counter-protection instead. Keep your core discard-madness engine intact since it's still your fastest way to close the game before they stabilize with Mulldrifter and Murmuring Mystic tokens.