An opt-in Hardcore ruleset for AzerothCore: one death, and it is over. You flag it per character yourself with .hardcore on, there is deliberately no .hardcore off, it is a one-way commitment.
What "over" means is configurable. By default (ghost, non-destructive) the character becomes a permanently locked ghost: resurrection and graveyard release are blocked forever, the body stays exactly where it fell. With archive the character is renamed after it has safely logged out so the name frees up again, but all its data is kept. And delete removes the character from the database for good, which you have to set explicitly because it cannot be undone.