Need to spin the wheels of the sacrifice mill
Selfless Spirit is the complete package when it comes to solving these main issues for white
If you get an extra rare or mythic rare card, its converted to either 20 or 40 gems, respectively
But if, you have reliable sources for die rolls, and you were going five color dice, why not slot in Dee Kay, Finder of the Lost
Honestly, when I think of Punishing Fire in the context of current Modern, it's either laughable (against Primeval Titan, control, Crashing Footfalls, 3/3 Dragon's Rage Channeler, reanimated Archon of Cruelty, etc.) or potentially even a positive, as a repeatable answer for the repeatable cheap threats from various Lurrus of the Dream-Den decks
For this upgrade project, we took only cards found in the starter deck and the other Rise of the Floodborn products we got on release day (for a full rundown of what we opened, see our Rise of the Floodborn review)