Did anyone beat 100% Steel Soul mode? I've made another attempt now after the Life Blood update. Risky, but I didn't want to go through the entire game again just to see what's new. And guess what, about 10 hours in I died to the Hive Knight, a new boss. The embarrassing bit is that he isn't even difficult. I'm just retadred and overestimated him, expected his attacks to be faster and kept dashing into him. He also spawns hivelings which would normally die in one hit. But these are invincible for some reason and you are supposed to dodge them. Cheap... Then I got nervous and couldn't find a good spot to heal. The End.
I don't know if I'm going to try again. More content updates mean more potential surprises that could kill me. Otherwise, with my route I'm confident I could make it to Radiance every time now.
1) Buy Quick Focus from Salubra as soon as possible.
2) Buy Fragile Heart (2 extra hit points) from the dude in Fungal Wastes. Come back later for Fragile Strength. You won't have enough notches at this stage anyway unless you want to play risky.
3) After defeating the Soul Master in City of Tears the game opens up a lot. Next you can get Crystal Heart without even having to fight Crystal Guardian.
4) In the lower right corner of Royal Waterways use the Crystal Heart to fly to Isma's Grove and get Isma's Tear. There is no real boss there, just an arena with normal enemies.
5) With Isma's Tear you can get Shape of Unn in Greenpath, a charm that lets you move while healing. Combined with Quick Focus you move even faster than normal walking speed.
6) Next boss would be Broken Vessel to get the double jump. But this is the perfect time to go on a collectathon and get up to 3 more hitpoints and 3 (out of 4 possible) nail upgrades! Then fight the pushover Broken Vessel.
7) With the double jump you can reach the Castoff Shell in Kingdom's Edge where you will fight Hornet again.
8) This opens The Abyss in Ancient Basin where you get the Shadow Dash.
9) etc. Doesn't matter now. The point is to get Shadow Dash for some of the more difficult bosses like Crystal Guardian.
A few more things to consider:
The third trial in the colosseum gives no reward except Geo and isn't required for 100%.
A warp point at a Stag Station can get you out of trouble.
Each nail upgrade adds 4 points of damage, up to 21. Fragile Strength further increases damage by 50%.
The shades in The Abyss can easily overwhelm you if you can't kill them in one hit. Fragile Strength is recommended.
Same goes for the Flukemarm boss and her flukeflies.
In the White Palace equip the Hiveblood charm. It slowly restores one hit point after you took damage.
I haven't tried it, but before you go fight a difficult boss you could technically stack up on those blue butterfly hearts. They are marked on the map. But you'd have to get back to the boss without getting hit. I don't know if they stay after warping. Sitting on a bench removes them.
I've also read that Hollow Knight's attacks now deal 2 points of damage per hit. Might not be a trivial boss anymore.