I am gonna to start DMing the D&D 5e adventure Tomb of Annihilation for a group of 5th-level PCs who just finished the Lost Mine of Phandelver Starter Set adventure.
One of the PCs is undead. By his backstory, he was killed in the gnome civil war and resurrected by the Velsharoon himself as an undead gnome with his soul inside of his dead body.
Now I understand that it means that he is affected by the Death Curse; he should have only 9 HP max, and after 9 days this PC would die.
It would be very stupid and unexpected death because it is mostly my mistake (as GM) that I didn't warn this player about that and allow him to use this PC.
Is there is a possibility to invent some solution or change the Death Curse effect to save him from it?
A description of the Death Curse:
While the death curse was in effect, humanoids on Toril that had been brought back from the dead began to waste away and eventually to die. Traveling to another plane or world did nothing to halt the wasting effect once it began.