Pthumerian Labyrinth Layer Three:Heart
The Watchdog is highly damaging, and cannot be taken down with molotovs like many enemies up to this point. Mastery of rolls is essential for this fight, as the majority of his attacks can be near-instant kills. However, his legs and head can be broken. You cannot visceral him, but this will allow for a couple seconds of free hits before he gets up. Breaking his head also weakens it, allowing for much more damaging strikes to this area.
- Dash - highly damaging, straight forward dash.
- Bite - right or left swing depending on Hunter location
- Fire fan - swings his arm and casts a fan of fire forward.
- Lava vomit
As more damage is taken:
- Chomp - chomps forward repeatedly while fire spews from his mouth
- Bite combo - continues to bite in various directions as long as the Hunter is at close range
- Double fire fan
- Slam - rears up and slams down, extremely damaging
- Explosion - charges up fire, then lets it explode in all directions. Also highly damaging. AoE
This is one of the more difficult optional bosses in Bloodborne, especially considering the first Pthumerian Labyrinth can be opened after killing the Blood Starved Beast. Take a weapon that you are comfortable with, but that has decent range, as well as a good number of blood vials as insurance. The best weapons that are guaranteed to be available are the Threaded Cane's whip, as it has a good vertical swing that can easily hit the Watchdog's head, as well as the Hunter Axe's halberd. Roughly half the time, the Watchdog will open with a charge, so start moving sideways as soon as you enter to make sure this doesn't hit you if the dog does it. After that, try to dodge around its attacks and memorize its attack patterns, as all will have telegraphs, and getting hit once can cost dearly. Attacking its head will eventually cause a stagger, which will allow you to hit it repeatedly for high damage. It's not possible to visceral the Watchdog, but breaking its head will allow you to wound it, making your attacks significantly more damaging, roughly triple what they were. However, by the time it stands up again, it will have full access to its alternate moveset, so you'll need to be much more cautions from this point forward. Staying on the defensive and getting in a few hits where you can will win the fight.
This boss is fairly easy if you are prepared properly and take it slow. By now you should have the Charred Hunter set in Old Yharnam. Equip it, it will boost your fire resistance which will come in handy. Next, use a far reaching weapon, because you will want to keep some distance between the two of you. Spears don't seem too effective because of the large arc of its movements that put it out of the short radius of a spear's strike. During the fight, stay within the beast's striking range and strafe-walk to the right. Its attacks are fairly predictable, when it winds up for the attack from the right side, time it and dodge left. If it winds up from the left, dodge left. Land one strike, two if you are fast enough. Repeat until dead.
You can also strike its front knees or its head a few times to stagger it. Try to get in as many hits as you can in this state.
If it's the Defiled Watchdog? You might need ~30-35 vit. Less if you can assure you don't get hit/play it really safe. Armor choice is probably Charred Hunter Set (and maybe a Top-Hat for lulz).
Get a long-reach weapon (such as Ludwig's 2h form or maybe threaded cane)…slash (R1 for Ludwig's, cause that's what I used) his face every time he's near you, dodge back to avoid his inevitable bite-attack, stay back, then run in (not sprint) to slash his face/head again when he starts to rev his head back to normal position, so you don't proc the multiple bite attack (combo bite attack, essentially). If you do use Ludwig's, don't underestimate Ludwig's 2h reach. It's pretty good vs this guy. If he starts barfing lava, you can run in to hit him a few times (legs?) but be sure to get out of there. He likes charging after that attack, especially when you're under him…which is an auto death.
Eventually, his head will 'break' and start to take 1k damage with a +10 Ludwig's (with appropriate stats) by simply R1. That is, until he explodes himself to rejuvenate his limbs/head. Then repeat the process to break it/them again. He should be dead by the second head-break (was for me). The first time his head breaks, he'll gain a new ability which is…more or less…throwing his head at you. I'm fairly certain this is a OHKO (maybe not for Depth 1 Watchdog), but make sure it doesn't hit you on a counter. Pretty much anything a boss does that hits you on a counter will probably kill you in Defiled…And even sometimes in normal with average/low vit.
His charge is really easy to dodge and has a pretty good visual cue. But if it hits you, you're probably dead. Keep that in mind. The Depth 1 Watchdog should be cake once you're a sufficient level. It can be killed just by hammering the f out of him. Breaking his head or not.
The arena is very basic. It is a large, flat, circular area with pillars near the walls. The Watchdog can smash these, so hiding behind them is useless. Otherwise, it is completely open.