Charlatan's Cure

You touch a willing or unconscious creature and enchant its mind, causing it to believe it is being healed, which spurs on its natural regenerative abilities. When you cast this spell the creature may reroll a failed saving throw against a poison or nonmagical disease (though it does so with disadvantage), or, if it is not afflicted with any poisons or nonmagical diseases that allow saving throws, to regain 1d4 hit points. However, this draws on the creature's own stamina rather than the Weave as true healing magic does, and thus it risks exhausting those reserves. Whenever this spell is cast the target must make a Constitution saving throw with a DC equal to the number of times this spell has been cast on it since its last short or long rest, and on a failure the strain on its body causes it to gain 1 level of exhaustion. Additionally, this spell is not potent enough to heal a creature with 0 hit points, at least not fully; if it is cast on such a creature the creature may choose to reroll a failed death saving throw, taking the new roll even if it is lower, but may not reroll a saving throw against a disease or poison and may not regain hit points by means of this spell (though it may still return to 1 hit point if this rerolled saving throw is a natural 20, as per normal rules). This spell has no effect on undead or constructs.

At level 5 the creature no longer receives disadvantage on rerolled saving throws against diseases or poisons, at level 11 the healing die changes from a d4 to the hit die of the creature receiving the healing (e.g. d8 for a cleric, d10 for a fighter, etc), and at level 17 the DC of the Constitution saving throw becomes equal to half the number of times this spell has been cast on a creature since its last short or long rest (rounded up).