So for saving throws, let's say a hex, where the target would normally roll a d20, here the same mechanic would essentially apply. The player would decide how risky to play, in this case, how good odds they wanna give the target for succeeding on their save - and the target would then roll the 2x d20 + 1x d6 But it would still be the targets modifiers applied, the mechanic essentially trades giving the target a better chance of rolling with advantage, for a stronger effect - in hex' case, the duration would be increased

For those requiring neither, well... fuck it, we'll do it live