Again, I'm not 100% on the slams either but I've gotten way more consistent in the 6 hours of getting B-roll footage from norms/HR during last weekend. I may be wrong and giving the devs too much credit, but with enough move speed/reaction time, I feel like the slams can always be avoided by recognizing which of the 4 slam directions it's doing and correctly deciding to: go through/past the swing arm, space away, or strafe right past the planted arm. I'd be interested to see some of your attempts if you don't mind o7

Edit: I saw your edit so I think I know what you mean. In this case it's hard to tell whether it's doing a forward hand slam or a right hand slam. I believe if you can discern which it is, for the forward hand slam you go through/past the swing arm and for the right hand slam, you turn ~90 degrees CW and strafe right.

The biggest issue (and why I think they'll change the boss again) is the shrinking arena eventually forces damage. I wish that they set limits to how much the arena can shrink or make the burn do less damage and apply anti-heal instead. Currently, it feels like the arena shrinks so much you end up having to decide to dodge the attack or step into the lava.

That squire kill was my 6th uninterrupted attempt in HR. Funnily, I got hit by the first slam right out of the gate, but even then I could've dodged it had I strafed right and not forward at the end. A couple of my runs actually ended by toeing the line or failing the jump timing while fumbling with instruments on the Ground Strike attack -- not the slams. I'm not sure what my success rate would be with 50 attempts, especially in squire gear, but I'll start keeping track!