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human
[DC General] What would happen if you put an undead creature into the Lazarus Pit?

We've seen the LP used to bring the dead back to life (often with some rather unfortunate mental health ramifications!), but as far as I know, it's always been *dead* bodies placed in the pit (or still-living, for some regeneration).

But what would happen if an undead creature went in there? For instance, would a zombie be "brought back" to being the (presumably) fit and healthy human they once were?

What if a long-living vampire were to get inside? Someone like Dracula, for instance? Would he become human Vlad the Impaler (or whoever) again?

Would it cure a werewolf of their lycanthropy? (I'm not 100% if they count as 'undead' so apologies if wide of the mark there.)
gpt
So here's the thing that isn't clear -- the Lazarus Pits aren't really that good at what people think they do. Here's the basics:

* If you're healthy, it kills you. It just kills you. It's not made for people who are healthy.

* If you're ill, sick or in any way dying harder than humans are typically dying, it heals you at the cost of your sanity. This can be wounds, cancer, *maybe* even lycantrophy. We've never seen a werewolf jump in.

* If you're recently deceased, it brings you back at the cost of your sanity. Your soul's still around, your body's fresh, this is usually okay until a couple of days -- a week tops, let's say.

* If you've been dead for a long time, you *turn into a zombie*. Your body comes back to life with no soul attached to it. You have a decaying, rotting brain; a still-beating dead heart and black oozy blood running through your cracked veins. It's a fate worse than death. This is what Bane *threatened* to do to the Wayne parents at some point, that's how bad it is. 

As for the vampire or zombie thing, it really depends. It would likely just cause them brain damage, if there is such a thing. It's crucial to know *where* their soul is, cuz the Lazarus pit has a really limited ability to pull souls back. It would definitely be unpleasant, unless you got something special going on.

The insanity effects vary. Usually you're stark mad and violent for a few hours to a few days depending on how severe your wounds were. In some cases, it even affects previously-had mental illness: the Joker became perfectly sane after dipping into the pit for a few hours, which made him horribly guilty of all his sins.

Ultimately, someone like Ra's who uses the Pits a lot is damning himself. He's destroying his own body and mind every time he dips in, and eventually the Pit itself will cause such a strain on his body that it will kill him. It basically gives you magic cancer.