This is a really good game! The combat system is fairly simple, different combat styles (mantras) differ in range, timing, and damage, but it works well and being able to combine a perk of a style with the secondary slot adds a bit of nuance to what you choose. Enemy variety though I think is what makes the game interesting and varied in its whole length, enemies are really well differentiated and they combine to create cool and unique encounters.
The combat mantras before thanatos do kinda feel unviable for the harder parts of the game, in particular the Descent, which actually I'm not sure was intended to be completable in a normal new game? There are a few issues in the game which don't become noticeable until you reach the most difficult encounters.
There's a big issue with visibility because some details can cover enemies, and you can't see their attack cues, and there's no good way to move them away, specially given the tight time constraint of the descent. Even worse is that in crowded situations enemies can obscure each other, which is not something that would crop up often in the normal game, but in the descent happens a few times, and it's all the more frustrating given that there you're pushed to play aggressively. Some combinations that appear, like the harbinger with small enemies, the harbinger can completely block other enemies from view. Also enemies attacking from offscreen is quite annoying, close to unfair given that projectiles are mostly fast, and the thing of moving the screen towards the enemy that shot the projectile that hit you wasn't a good idea, because it obscures the most important threats around you and disorients you.
Also enemies can attack you instantly when they teleport next to you, which can be a bit unfair. They can also attack instantly when you use a rewind, and attacks from before remain after a rewind, so you can get hit instantly upon rewinding, it kinda seems like enemies should wait after teleport or rewind, and previous attacks be wiped off.
Another thing that sticks out mostly in crowded combat is the soft lock on, which I think is the worst issue of the combat in this game, because it takes a lot of control away from you, and is sometimes finicky and targets unintuitive targets. It can cause things like stop you from capitalizing on a break or parry because suddenly the lock on decided to target another enemy, it really feels awful.
Some attacks seem to respond inconsistently to dodging them, you dodge right through the attack, but there's no slight slowdown in response to dodging, or big slowdown if you have the virtue that does that, and if the enemy does two consecutive attacks quickly, it catches you with the followup during your dodge recovery. It feels a bit buggy.
Something that I'm pretty sure is a bug is that the prototype enemy, that red kid that teleports, when you break them, they become completely intangible to your attacks. That same enemy, and the other kid enemy that appears in the descent, kinda seems to attack unreactably fast? I'm pretty sure I'm not just old and slow, because even pressing space anticipating the attack I've gotten hit, maybe something with input lag? I'm playing on speed 1.1 and didn't try slower, not sure it's related to that anyway, but if speeding up the game makes it not work very well maybe the option shouldn't be there?
Those fast attacks wouldn't be a problem, they just make you play conservatively, but that's not something you can do in the descent, and coupled with the ocasional visibility problem, makes fighting fast unreliable, so overall the descent on new game, specially the later parts with lots of fast kid enemies and lots of bosses, feel like gambling, sometimes you get lucky and break them enough to kill fast, but you don't have means to kill really fast and reliably in new game. Maybe the tools you get on ng+ make it doable, I'll try that now, but it really doesn't seem made for normal new game.
After I completed I had seen that challenge difficulty should be unlocked, but it didn't appear for me, not sure if it appears later or it was an error.
Anyway, the descent frustrated me a bit because it exacerbated those issues, but the entire rest of the game is really good, when you get used to it the combat can get really fast, and challenges are varied and interesting. It was a really interesting game to play!