Issues with A2 Colossus boss fight

A few things:
- the auto aim while on WASD was very strong and made my skills aim 90 degrees away from where my cursor was aiming. My monk kept missing frozen locus with glacial cascade
- Got to 99% freeze buildup and the counter just reset with no obvious action slow. Potentially a bug?

I'm on this boss fight right now and man... I don't think they playtested this fight at all with a melee character. With mouse movement (not WASD), my character (a Warrior) tries to attack nothing all the time. He insists on running over to attack an arm that is out of reach. I'm spending most of the fight swinging at nothing because of whatever this auto targeting nonsense is. And the character displacement, it's glitched me off the platform into the abyss so many times. Fortunately it seems to kinda desync you back on the platform, but it's still jarring.

And then I just get one-shot by an attack because I have to be in melee range to do anything. My last attempt I died because the little monsters started coming in and just shotgun froze me in place.

Interestingly, also playing a melee build and the hitbox you are trying to hit with your attacks is actually pretty massive. Even if the hand is up off the platform it will still do damage.

Unfortunately, I specced into 2x 2hand weapons and a bunch of stun nodes, and even with +165% stun on tree and spamming high stun moves I only got him to 90% stun bar the first time I killed him. I have seen similar problems from others, where ailments are not proccing, or never get high enough to proc.

The only attack from him that I really have had an issue with is the one where he raises his left hand back and then slams forward diagonally with the blade, this seems to 1-shot even my tanky warrior with 850HP and oodles of armour. That one attack accounted for all 7 of my deaths to the boss as the telegraph looks very similar to 3 other safe attacks and the hitbox comes out so fast that I struggle to consistently get out the way. On the attempt that I killed him, he never did the attack.

This is the only boss that I have encountered so far where I pin my success to luck more than learning the attacks and working around them. With other bosses, controlling the stun bar and delaying attacks to allow me to interrupt dangerous ones has been super cool and interesting. But that just isn't an option here.

To follow up further on this, I put more investment into stun and got a weapon with stun bonus implicit and explicit. Went back to test it out and managed to fill out the stun bar at about 50% health, upon which NOTHING HAPPENED.

It didn't even clear the bar, the second half of the fight the boss just had a nice decorative yellow bar under their normal health bar which had no impact on the fight at all.

If you are going to make a boss stun immune, it would be great to have some sort of communication for this, instead of making it seem like it IS stunnable, just hard to do so.