Slow assimilation being not really slow at all given how fast the mobs are and their ranged spits and other such stuff is kinda ouch? I'm not saying remove it, but have the scaling not be as catastrophic?
Like only apply 5-10 seconds a hit, then after reaching 20 or 30 seconds or so, upgrade the potency and half it and repeat? specific moves like spit could apply more time to it faster, or purely offensive moves like spines shouldn't cause it at all. While higher level foes should apply more also, but not simpler tiers. The max time should also not go much higher than 30 if you're gonna stack it. As getting away but then still having no choice but death for a minute+ with an assimilation 10 application is just massively rude.

I'm also noticing that you seem to apply the effect despite no damage being dealt. This is an issue with mods that allow blocking and/or damage negating such as War Dance's parrying. Blocking with a shield also seems to still allow the effect go through, unless I just already had the effect on me to begin with which feels annoying, given how fast some of the creatures are where blocking is really your only saving grace short of making distance in some other special way you might not have.

It is already planned to be rebalanced in a future update. The fact that it applies when you block it is deliberate though, I found that shields made the mod a little too easy. Some mobs like Split Face and Palmer Things are too dangerous and need to be nerfed which is why this feels unfair, it's meant to encourage learning attacks and getting better at dodging them instead of just tanking them but some enemy attacks just aren't dodgeable right now.

Apologies for the slow response, suggestions and bug reports are usually posted on discord so I don't check here often

It is already planned to be rebalanced in a future update. The fact that it applies when you block it is deliberate though, I found that shields made the mod a little too easy.

Ugh. Then apply shield break and balance it. so you can block one attack but then need to evade some more.
but if you want to push that angle, please for the love of god allow the mobs to be affected by slows. I've tried freezing them with an effect that forces powdered snow freezing or just chucking slowness over them, they are still so fast that they're able to keep up even with my definitely non-vanilla cat leaping and elenai dodging combos. they're insanely fast when they really want to come after you.

Some mobs like Split Face and Palmer Things are too dangerous and need to be nerfed which is why this feels unfair, it's meant to encourage learning attacks and getting better at dodging them instead of just tanking them but some enemy attacks just aren't dodgeable right now.

Split face? the guy that tethers you when you're close? and palmer thing? I'm not sure what he does, I only did a few test fights outside of actual playing to learn how to murder them.
But yeah, nothing is really dodgeable, I can't even really knock them back for the most part, you made them as hard as rocks even when they're on fire thats only a portion of the battle and if they so much as self extinguish they just get all their damn health back unless I hose them down with an anti-healing effect in the interim...
My only saving grace is that I can parry a hit or two but I still get ticked with assimilation so hard that I start raging eventually. Since parrying doesn't follow MC shield mechanics, it should just block the attack and negate effects at the cost of posture in Project War Dance. I recently released a video you can scrub through if you want to see my struggles against them in a non-vanilla setting.

From the pinned comment, try these points:
38:05
50:50
55:50
59:10

Apologies for the slow response, suggestions and bug reports are usually posted on discord so I don't check here often

it's alright, I been slacking off forgetting to check my github replies also cause of work and distractions in between. :V

Ugh. Then apply shield break and balance it. so you can block one attack but then need to evade some more.
but if you want to push that angle, please for the love of god allow the mobs to be affected by slows. I've tried freezing them with an effect that forces powdered snow freezing or just chucking slowness over them, they are still so fast that they're able to keep up even with my definitely non-vanilla cat leaping and elenai dodging combos. they're insanely fast when they really want to come after you.

They should already be affected by slows. The shield break is a good idea though
The next big update is going to add the first boss so I'll be playtesting a lot of combat to make it feel more fun

But yeah, nothing is really dodgeable, I can't even really knock them back for the most part, you made them as hard as rocks even when they're on fire thats only a portion of the battle and if they so much as self extinguish they just get all their damn health back unless I hose them down with an anti-healing effect in the interim...

I wouldn't go so far as to say nothing is dodgeable, from my testing and from previous community feedback most of the mobs have been fine. It's specifically the Split Face (the big creature that looks like it has 2 faces fused together) and the Palmer Thing (the guy that tethers you) to a lesser extent that I feel aren't fair. You can outrun most of them, just right clicking with flint and steel sets them on fire, and flaming arrows exist as an early game ranged option before you get access to the flame enchant

Since parrying doesn't follow MC shield mechanics, it should just block the attack and negate effects at the cost of posture in Project War Dance. I recently released a video you can scrub through if you want to see my struggles against them in a non-vanilla setting.

Since vanilla is the focus, there are a lot of planned fixes and improvements that take priority over this