Progression triggers

[Festive Mints]

I've been wondering just how many triggers there are when you progress through the game,
exactly what events trigger them, and any repercussions they might have.

What I mean by this is, for example how when you first kill a Dreamer/Collect the Monarch Wings it will turn the Forgotten Crossroads into the Infected Crossroads, or how killing all three Dreamers will unlock the White Defender boss and stuff like that.

I'm fine with stuff that spoils the main story as well as the Grimm Troupe and God Seeker stuff since I watched a whole bunch of videos about them before I decided I wanted to play the game myself and pretty much know most of the major events already.

The reason I'm asking about this is because I'm always worrying in the back of my head that if I activate some trigger, I will miss out on something and will have to wait until I replay the game to be able to do it, even though I know it's irrational.

Any answers are appreciated and will help put my stress factory of a brain at ease.

[Darc Vader]

Killing all the Dreamers also allows Mr. Mushroom to spawn.
Myla has 3 progression triggers:

• Vengeful Spirit
  
• Soul Master
  
• Crystal Heart

Zote must be confronted in the colosseum and Bretta must be rescued to unlock Grey Prince Zote
The Moss Prophet is killed by the infection at the same time the Crossroads are infected.

Those are really the only other one’s I can think of off the top of my head, other than basic stuff with npc storylines and mutually exclusive stuff that requires a second playthrough anyway.

Edit:nothing major is missable aside from those mutually exclusive things. Other than those, the only stuff you can miss is dialogue, and a single Arcane Egg.

[Szaal]

The only things you can miss and lock yourself out (obviously big spoiler here, but not gonna blot my entire post):
1. Zote bad (good) arc: leave him / help him on Vengeful King sequence when you first encounter him.
2. First ending, The Knight becomes true vessel: unobtainable once you visited the Birth Place and acquired Void Heart
3. Second ending, Hornet seals herself with you in the Black Egg: unobtainable if you chose to enter the Hollow Knight's dream during git gud sequence.

4. Letting the Blacksmith lives: unobtainable if you kill him after evolving your Pure Nail.
5. Fourth ending EX (fifth ed?), Godseeker bursts by the void, but immediately tamed: unobtainable if you give fragile flower to the Godseeker.

Now I think about it, the only endings you can get yourself locked out are just the first and the fourth ed.

[Szaal]

Oh, yeah, there's also Myla though I'm not sure about her trigger.

[Darc Vader]

True about the endings. You can get all of then on one file, but to do so you have to get the base ending before you progress too far, and complete all of Godmaster before giving the Godseeker a flower. As long as you do those endings first, all of them are doable since you can just load your save back up and keep progressing.

[kanna]

Endings are well covered above.

Grimm Troupe DLC has two endings (to the DLC content, not the game). You probably can't get them on one save file. I haven't tried, but I think there are auto-saves involved that can't be avoided. If you're planning on banishing the troupe, make sure you upgrade all your fragile charms with Divine first. (If you're playing on Steel Soul mode though, it won't matter.)

Myla (NPC) Progression:
#0 (Talk to her before doing the stuff below)
#1 False Knight's defeat and/or Vengeful Spirit progresses her dialogue one step.
#2 Soul Master's defeat and/or getting his associated ability is the next step.
#3 Getting Crystal Heart will immediately progress her to her last stage.

As mentioned above, there is a missable arcane egg, behind a conspicuous door in the Abyss. Bump into a few spikes looking around if you have to, but get it before picking up the charm or it will be lost forever. General location if you're not sure which is which: Egg's at the lower middle right; the charm is at the upper right.

I'll add to this if I think of anything else.

[Amberstar]

Originally posted by kanna:

Endings are well covered above.

Grimm Troupe DLC has two endings (to the DLC content, not the game). You probably can't get them on one save file.

Yes, it's impossible to get both Banisment and Ritual on one save. I recommend going to

AppData > LocalLow > Team Cherry > Hollow Knight

in your file explorer when you're at that point, look for the user.dat file that corresponds to your save (user1.dat is file 1, user2.dat is file 2, etc.), copy it and paste it back into the same location, and rename it to not correspond to your main file. Then you can get one ending (achievement) on the main file, and one ending on the copy.
I recommend getting Ritual on your main and Banishment on the copy because not only do you have to wait until you get to Godhome to fight NKG if you banish the Troupe, you also lose Grimmchild forever on that save. And instead you get Carefree Melody, which has a chance to negate damage, but it's extremely rare for it to do so, so it's not worth it.