Beat the game's superboss, who is basically DIO voiced by Alucard
*.
Setup was a Betelgeuse gun with diamond bullets and Recycler Hat(infinite ammo, pain in the ass to get), Flame Armor, Solomon's and Traverser's Rings for as much attack power as I could. Equipped shards were Welcome Company(to shield me during his timestop), Accelerator for mobility, and a maxed out Firearms Expertise for gun. Betelgeuse is the third-best gun, but second best has issues with actually hitting and the first best is a helluva money grind. Basic enemies outside the main base were taking over 300 points in damage per shot. The boss took a little over 190, and has ~10k.
The main difficulty from the fight is simply reacting to his attacks quickly enough. First move is to flip the room over right away, which avoids the main danger of contact damage. His fire pillar and ice shard attacks can be dodged by running to the opposite side of the room before they fire. The only real danger is his jump attacks which can hit the ceiling, and of course, his timestop. It's pretty much impossible to dodge that, but Welcome Company can block some of the hits.
After one or two failures, the whole fight felt easy.
Bloodstained: Ritual of the Night. Gained not only the power to stop time, but a ton of stat boosts from looting his books.
EDIT: Broke the game some more before fighting the final boss. Took me waaay too long to find the Augment Gold shard, which causes money drops to increase dramatically. By about 100x more. Quickly got the Gilded Youth achievement, an achievement that, according to Steam's statistics, is the third-rarest non-DLC achievement(I don't know if the Overlord achievement requires the DLC) that's been gotten, with only 16.3% of players having it at the time of writing. Then I spent pretty much all of that money on stuff to enhance other passive shards - fun fact: if you max out the rank of a passive(yellow) shard, it becomes a permanent skill(white) shard that's always active... and you can still equip the yellow one to double up. It also took me way to long to realize that you needed to get extra copies of shards before they really get useful.
Equipped two Traversal Rings, which boosts stats based on map completion - I have literally one single chunk missing for 100%.
Bloodstained: Ritual of the Night. After clearing the final boss, I took on Boss Rush. Best times are 52.84 for Course 1, and 1:33.78 for Course 2. I probably could have done better on Course 2, but Gremory slapped me around a bit too much.