The Boiler is 80% backed by BUSD, which is fully backed by the dollar. The remaining 20% is backed by SAUNA. For example, if you try to get 10.0boiler, the boiler's Minting engine will ask for 10.0BUSD. From that 10.0BUSD, you keep 8.0BUSD in the Boiler contract, purchase 2.0BUSD worth of SAUNA on Pancakeswap, and keep the purchased SAUNA in the Boiler contract.