First attempt - Schrodinger's Death Save: Quantum Die
The concept was a death save dice (11 success/9 failure) with one success and one failure only visible under UV light (natural twenty/natural one). If a blank face came up, the player could choose to skip or reveal. If they reveal, the skull is a critical fail (two save failures) and a heart is a critical success (back up with 1hp). If they skip, the roll is neither a success nor a failure; the turn ends without adding to their track in either direction. I like the sense of theoretical agency it would add to the process, plus the idea of having a qubit die face tickles me somewhat.
The obvious problem is that despite using a "clear" UV ink and using a flat-faceted outer blank, the UV face is still discernable unlit from about two feet away... makes the decision pretty easy. If anyone has any ideas for techniques to make the unlit UV face less readily visible, I'd love to hear them!