OneRedRook
Explorer
@OneRedRook
To me, your DCs in combination with your HD costs look fairly high. But I'm no expert in relation to 5e, so maybe my impression is flawed.
I've got no quibble with your structure.
Having had a chance to reflect on this, I agree costs are clearly way too high, to the point of being punitive. It's also far too fiddly. I'm happy with the two-round consequence and the DCs, but success should just be "target spends one HD for hit points" and failure should be "petitioner spends one HD without effect" in each case. The points about additional bonuses and zero HD still seem OK.
I initially thought this might be more interesting (I mean narratively and mechanically, not as a comment for this discussion) than it probably is, which I suspect speaks to the 'nothingburger' comment above.
I realise the DC 23 case might reasonably put this out of reach for some characters, at least without promising a lot in exchange, but that seems fair. Given that I would accept either Wisdom or Intelligence for the ability roll, we're looking at someone who cannot manage more than a +2, which suggests they have no particular aptitude with religion, aren't well-read enough to know what might appease the gods, and don't have enough common sense to know whether they should be meddling like this. I don't think that person is favoured by the gods.