I finally beat the Hydra and then made it to the next boss in Elysium. I lasted a while and got the guy down to around 25% and the other down to around 33%. It seemed like they can take a lot of damage because their bars moved very slowly. Got the 500 darkness to get another brig back from the dead ability.
Those (chaos?) pits that start that to appear where it makes things harder for a bit then get a boon - is it good to take some early ones to make the later run easier? I generally make it to the hydra now even if I only beat it for the first time today.