Arnwolf666
Adventurer
Niiice. Does the group you DM hate you?What about most of them?
Zombies can inflict 1 level of exhaustion on a critical hit. If you are at 0 HP, instead of giving you 2 death saves, they give you 2 levels of exhaustion.
Ghouls attacks also give 1 level of exhaustion on a critical hit, but also if you fail the initial paralyzed save. Ghast the same, but the Stench also drains you, and each failed Paralyze save (not just the initial) gives you 1 more level.
Just have your life ... drained ... out ... of ... you.
If you die from undead exhaustion, and proper burial rites do not occur, you can rise as an undead (roll 1d6: minutes, hours, days, weeks, months, years, then roll 1d100 for how many)