(mainly directed towards aslp but applies to 1xx lp as well) Broken Vessel has 525hp; stagger values are 9 hits for combo (<1s/hit) and 13 otherwise; headbanging phase starts for the first time once you deal 155 damage, so 4 shade soul hits is always enough to trigger it.
You want to always start the fight by firing 2 shade souls (where you do a small jump between the first fb and the second one), which has a few different outcomes: -both shade souls double or one triples and the other singles (e.g. whilst bv is on the ground or dashing towards you): For this case get 4 nail hits before the headbanging phase starts*, and then you want to get 1 nail, 1 pogo and a ddark, followed by 1 upslash, one pogo and another ddark, followed by a pogo and a ddark, finally ending with a ddark.
-only one shade soul doubles and two single hit: For this case there's pretty much no risk of staggering before the headbanging phase starts, so try to get 7/8 nail hits in and then do your first ddark. After that you want to do a sequence of 1 upslash, 1 pogo and a ddark (all) twice, which will send the boss into a staggered state. Depending on wether you got 7 or 8 nail hits at the beginning you can either directly ddark the boss (or shade soul double if you're feeling spicy) or you'll have to do a pogo into the ddark.
The two most common cases are the ones described above, but there are some other misc starts to the fight, for example, where you get "bad rng" but the 3rd shade soul doubles (or even triples in some cases) or you try to go for three doubles. Essentially, if you get 5 shade soul hits at the start of the fight you want to follow the 1double2singles case (soul gathering a little less strict), but instead of finishing with a ddark you can get enough soul for a last shade soul. *try not going for more than 4 because stagger is at 9 combo hits (or 3 hits if you start with 5 shade soul hits)
Been doing this for a while, but forgot to make a strats post about it ๐
Saving some soul out of broken vessel to start off Lost Kin with a double makes the end of LK much more consistent since you don't run out of staggers.
Ideally you get exactly 4 doubles on BV so your damage lines up and you get to enter LK with 5 hits.
Otherwise, when BV is 1 shade soul away from dead, just hit it until you're at 7 or 8 hits of soul, then shade soul.
This saves around 3s optimally in Lost Kin, but probably saves more on average.
You can do your cdash from this far left (Visual cue is when your right side is lined up with the tall blade of grass) and still clear all of the lightspawns on the right, due to the large hitbox that spawns behind you. This often lets you clear one or two extra to the left of BV before they get to jump, which can save a little time because you don't have to wait for them to land in BV's head
quick kill w/o needing to follow stagger. get 1st 4 nail hits asap, wait for headbang attack. make sure 5th nail hit doesnt stagger bv out of headbang, then buffer 3x pogo ddarks, finally upswing -> pogo -> final ddark.
if you get an instant headbang attack, just do the regular kill. you wont have enough time to get the 5th nail hit and finish all 4 ddarks in time before the headbang attack finishes, causing it to stagger and be pushed out of your final ddark
if you framegreed~~ the 5th nail~~ everything super hard, can kill w/o triggering stagger (during headbang) but yeah that sucks lol
small change in strat over the snek yumps when leaving the mawlurk room that i mostly see. much more lenient jump timings and lets you buffer compared to walljumps which have no buffer.
slightly faster on avg for me (~0.02s), and almost 0.2s faster when comparing my best attempts of each.