What is the cheapest you can cast a repeated Bellow's Breath with Ezreal Prodigy and/or Vex Cheerless cost reductions?

The cheapest you can cast a repeated Bellow's Breath is 1 energy and 0 power (1e0p), regardless of how many Ezreal Prodigys or Vex Cheerless you control in combat. This is because of the new discount ordering rule (Rule 356.4): Ezreal's component-specific discount applies first to the energy component, then Vex's total-cost discount applies to the remaining total. The math prevents the cost from reaching 0.