As a skeletal man being melded with some sort of equally skeletal beast, The One Reborn looks like he came straight out of a modern Resident Evil game. His attacks can be pretty damaging but The One Reborn has a rather limited move set, making him one of the more manageable bosses in Bloodborne.
When the fight starts, the first thing you’re going to want to do is run past him and head up the steps to your left. There are 6 spell casters on the second level of the arena and they can make the fight a lot harder than it needs to be. You’ll find 3 spell casters on either side of the floor, ringing a bell. When you attack them, be careful not to knock them off the edge as that means you’ll probably have to deal with them again when you go back to the ground level. While you’re attacking the spell casters, also watch out for dark projectile attacks from The One Reborn. Try to dodge roll your way to each spell caster and you should get through this part of the fight relatively unscathed.
Now that you’ve taken out all 6 spell casters, it’s time to properly face The One Reborn. As I’ve already mentioned, this boss doesn’t have a very expansive move set so you’ll be able to learn his attack patterns pretty quickly.
His most common attack is a ground stomp that he executes with his many limbs whenever you’re close to him. The stomp itself doesn’t do that much damage to you, but it can be pretty devastating when he does them in rapid succession. When The One Reborn begins stomping, start quick stepping around him to swiftly dodge his attacks. Things only really get dangerous when you start seeing these dark, dead bodies start dropping on you from above. One hit from the dark matter can easily shave off about a quarter of your health bar and these attacks come in huge volleys. When this happens, you’ll want to start dodge rolling or quick stepping to get out of harm’s way.
The One Reborn has another powerful area-of-effect attack that you need to watch out for. When you see the boss glow red, start quick stepping backwards to create as much distance as possible between you and the boss. You’ll have about a second before he releases a powerful burst that can take off a huge chunk of your health bar.
Once you’ve gotten the boss down to about half health, he’ll start using a new attack where he vomits venomous liquid all over the floor (charming, I know) that damages you upon contact. This is a very dangerous attack, as the liquid will cover almost the entire ground area. When you see The One Reborn rear his head upward, get ready for the vomiting attack and shield yourself from damage by running to the nearest flight of stairs. You should wait for the liquid to dissipate before rushing back in to continue your assault.
At the beginning of the fight, once you’ve taken out the spell casters, you can perform a leaping attack on The One Reborn from the second level. You’ll take a bit of fall damage, but a leaping attack should deal about a thousand points worth of damage to the boss. A good strategy to employ is to keep to his side and pound away at him continuously. The first half of the fight should be relatively manageable as long as you dodge out of the way whenever he starts the ground stomp.
Occasionally, The One Reborn will fall limp when you’ve dealt a good amount of damage to him. I’ve found that he seems to be particularly susceptible to bolt damage, so if you have a Bolt Gemstone or the Tonitrus, these will come in handy against The One Reborn. Alternatively, the Oil Urn and Molotov Cocktail combo will also work wonders in this fight. When he falls limp, make sure to hit the skeletal corpse for extra damage.
The One Reborn is a pretty slow boss who has very bad mobility. Use this to your advantage and dodge his attacks accordingly. However, even though he’s slow, never get complacent, as he can deliver a world of pain to your hunter if he catches you with any of his attacks. As with all the previous bosses you’ve faced in Bloodborne, don’t get greedy with your hits, and always back off when you see him winding up for a big move. It can be tempting to stay at his side the whole time and wail on him with attacks, but remember that he can fend you off with his AoE moves as well.
Take your time, dodge accordingly, and The One Reborn will be another one in the bag.
For more guides, tips, tricks, or advice feel free to check out Twinfinite’s Bloodborne wiki.