I’m not 100% sure I understand the behaviour you’re describing, but it can’t be done with current roll condition syntax alone.
I think, it might be doable with a customised d100 however (though the actual d100s take a long time to roll).
- Make a new d100, call it something unique (eg “merp”)
- On faces 96 and up, use string values of “[96+merp]”, “[97+merp]”, etc
- On faces 5 and below, use the string value “[5-merp]”, etc
Though like I say I’m not sure I understand exactly, since this can mean alternating additive and subtractive explosion on the lower rolls, and it doesn’t incorporate any rerolling.
Either way I think that is as far as you can get in the app right now without doing things manually, sorry!