I was wondering but how exactly is the avatar state very useful for example if an avatar like Korra gets poisoned by a metallic based venom?
The Avatar State, yes, is a defense mechanism designed to empower you with skills and knowledge from your pasts lives and stuff but if we think about it, it would only ever be good in attack or if you were nearly killed by some huge fire blast of some magnitude.
When I think of how the Avatar State was shown in both Avatar the Last Airbender and Legend of Korra, I think of the Avatar State as some type of safety shield. It gives you the wisdom and knowledge and power which practically make you invincible.
If you were poisoned however, the avatar state can't really do much. Suddenly becoming powerful at bending and being able to destroy a mountain out of lava really wouldn't save you from getting killed, would it?
So if Korra stayed poisoned while in the forced Avatar State, would that mean it would have somehow healed her or would she have died anyways and if she died, would the avatar cycle had ended?