Talk:A Challenge/@comment-27749857-20160207040531/@comment-27749857-20160218035505

I was able to access the arena again in NG+, so at least there's that.

I decided to go back and do a bit of testing, and i was able to reproduce the bug. It turns out that if the game saves after the hydra has spawned (it doesn't do this every time - it almost seems random) and you load that save, then the gate behind the hydra as well as the gate that you entered from will fail to close. Upon defeating the hydra, the gate behind you that is open will close, as opposed to opening, obviously. It seems like the game simply switches the door from one of two possible states (open/closed) to the other when the hydra is defeated, but it doesn't expect for the door to be open at the time. Even though this lets you exit frontier cavern while the boss is still alive, reentering does not seem to fix it - even though the cutscene in which the hydra enters plays again, the gates still do not close. The only solution seems to be to load a checkpoint save. Otherwise you are effectively locked out of most of frontier caverns until your next post-game cycle.

tl;dr - If you load a save and the hydra has already spawned, immediately load your last checkpoint save. Otherwise, you will be unable to fight the hydra again until NG+ (or BBI).