I've been reading the Chamber/Spawn Manipulation guide, and I understand that standing in certain corners makes enemies less likely to spawn far away. I have a few questions though:

1. Do I need to be snug in the corner for this to work, or do I just need to be in the general area? For example, room AC19 has a range you can move around in while you spawn manipulate. Room AC15 however has a tighter orange circle-- do I need to be inside the circle, against the wall, or just near the circle to make it work?

2. Do you have any strategies to making spawn manipulation flow more easily? Do you fight on top of a corner while enemies spawn in, or do you move freely and stand near the special corner in between waves?

I'm guessing answers will vary based on the room and enemy types, but I'm open to any advice.

1. There isn't exact places you need to stand, but generally things can't start spawning further than just offscreen. I don't believe there is exact "areas" where if you are beyond a line, enemies can't spawn in certain places, so a little bit further into the corner will make enemies spawn a little bit closer, if that makes sense (if I'm wrong somebody please correct me). The reason for the tightness of those circles is just a matter of how much you care about exactly where things spawn, which is based on the size and shape of the room. AC19 is quite skinny, so as long as you are at one end, you can basically see all enemies that can possibly spawn at once when you move out of the manip area. AC15 is more square shaped, and so if you simply went to one side rather than a corner, enemies could spawn far up or down. Spawn manips are more important on bigger maps or maps with gaps like AC15 because enemies can be really hard to find if you don't.

2. This is really hard and something you will work on your entire speedrunning career(?). In general, get a sense of how long a given wave is going to take to kill, and route your killing of enemies so that you can put yourself into manip positions just after you kill the last enemy of that wave. In general, you move somewhat freely during waves, in whatever way your weapons requires, but you want to be really conscious of how long waves take; it sucks to kill a wave sooner than you think and then you're standing in the middle of the room when the next one spawns. For certain enemy types I might just stand in a corner, though; when the room is something like "a bajillion unarmored numbskulls" (we've all had those), then not all the enemies in the wave are going to spawn at once. (for the record, "wave" here refers to waves separated by complete gaps in any enemy spawning, there can be up to 3 waves, with the 2nd if there is 3 being the shortest). For these types of enemy spawns, because there is no time in between enemy spawning to go back into corners, you should just try to stay in them. You also usually want to try to kill all the enemies in these sorts of "trickle waves" at the same time, so that they aren't spawning 1 by one while there is some alive in another corner. For instance, in AC24, if you get an enemy type like unarmored witches, there can often be one spawning in the top left corner and a couple over on the right side. If you kill the one on the left side early, then another might spawn there, then you have to wait for it to spawn and kill it, then maybe another will spawn and then you have to kill it, then you have to go over to the other side and kill the other 2--and that's just one wave. In order to kill the enemies closer to the same time to allow the trickled enemies to spawn faster, it can be good to go past the first one (depending on weapon) and then kill them from afar when they're behind you and then quickly kill the two on the right.

Sorry this ended up long, hope this helps; manips are one of the most difficult and most nuanced parts of speedrunning.

This is exactly the type of reply I was hoping for! Thank you-- not too long at all.

You answered a lot of questions that have popped up in my head while practicing these last couple days. Like how to deal with enemies that trickle in as you work your way through a room.

Overall, this whole thing is becoming more intuitive for me-- at least in Tartarus. It's reassuring to know it's a more nuanced topic and not an exact science.

Based on your advice, I think I'll prioritize learning the spawn manipulation points for bigger rooms first.