Given that it's a staple of both gothic and cosmic horror stories, it's kind of shocking that Bloodborne's main game didn't have a creepy hospital. Well, guess what! The Old Hunters certainly does! The Research Laboratory is a very large area with a massive central staircase-hub where patients who typically have had their heads transformed into large, shapeless masses roam the balconies and rooms.
Definitely not as tough as the areas before Ludwig, this area is much more about navigation than combat, as you'll need to figure out which stairs to climb and which ledges to drop off of to get around, not to mention that it all shifts a bit when you raise the entire stair-structure.
There's a quest in here that I will have to do a bit more work on involving the collection of Brain Fluid (yep, gross.)
The boss of the area is, collectively, the Living Failures.
This is a group of misshapen, headless beings who stand around what looks like an enormous collection of sunflowers. To start with, you'll only have one. Each individual Failure isn't actually that tough - one its own it would feel pretty reasonable for a "trash mob," to borrow terminology from WoW.
I believe that these guys are divided between melee Failures, who hit relatively hard but can be dodged without much trouble, and caster Failures, who will shoot arcane stuff at you.
Over the course of the fight, the number of Failures up climbs to 5. If you kill one, another will rise until their entire shared health pool is exhausted. I believe that you'll effectively do double damage if you hit two of them with a melee attack because of this, but you'll probably want to keep on the move and avoid letting them hit you.
They have one big attack you need to look out for, where they all raise their hands and begin to channel a kind of meteor storm. But at least in my experience, all the meteors were coming from one direction and could be outrun, out-rolled, or you could just hide behind the giant flower.
I didn't one-shot this boss, but it only took me three tries, which in a game like Bloodborne feels pretty close (after like 20 attempts on Ludwig.)
I've also got two more bosses to fight pretty much immediately. First, I got Laurence's skull from the Surgery Altar (which serves as an elevator between Ludwig's area and the hospital, and has some of your typical Soulsborne elevator shenanigans going on - hidden compartments and all.) Bringing this into the cathedral where the previously inactive flaming Cleric Beast, who is in fact Laurence, founder of the Healing Church (or at least a Nightmare recollection of him,) was reclining at his altar will activate the boss. I've only made two attempts on this guy, but he's got a similar moveset to the Cleric Beast but these attacks also do area-effect fire damage.
I think Laurence is "optional," but obviously I want to down every boss, and technically the whole Old Hunters DLC is "optional" if your only goal is to beat the main game. Haven't looked up what he drops.
Of course, having beaten the Living Failures, I'm also immediately at the subsequent boss, Lady Maria, who guards the Astral Clocktower. I've made a couple attempts on her as well. She's basically a really strong Hunter who uses the Old Hunter Bone to flash-step around a lot and has some nasty charges and combos. At 50% she impales herself with her own swords, giving them much farther reach and some ranged attacks. She can be shot and staggered, but the timing is tricky.
Anyway, I've got bosses to work on and I definitely have a few items to go back for, like the Brain Fluid quest and the Gattling Gun. I've gotten a lot of the hidden items, though, like the Church Cannon and the Church Pick.
I'm loving the Whirligig Saw, but I'm also wondering if my next character should be more Skill-based (probably sensible) or more Arcane (partially just to wield the Holy Moonlight Sword and maybe play around a lot with elemental gems.) The Whirligig is fantastic and totally versatile, but as a result, all the other weapons I'm getting are sort of superfluous.