Why can a boss slam track for literally 3 seconds before hitting?

So was just fighting monkey in HC act 3. I see him flash red, roll behind him when the flash disappears, he still does a full 180 to drop onto me before I can re engage the roll. With a slam that can do over 1k damage. Seriously, if you are going to have slams that hit for your entire health bar no matter what armour stats you have (had 30% damage reduction by the tooltip), then you CANNOT HAVE THEM TRACK YOU LIKE THEY ARE AIMBOTTING IN COD.

Also, unrelated note, but please change how it displays your defenses to be based on the damn monster level NOT YOUR LEVEL.... YOU CANNOT HONESTLY EXPECT ME TO BELIEVE THAT IF I GO BACK TO ACT 1 WITH 1k EVASION I STILL ONLY HAVE A 20% CHANCE TO EVADE!!!

On the tool tips, I thought POE2 was a good opportunity for them to make an improvement. In some other aspects, they have made improvements on the information that is conveyed to the player, but I don't think it has been improved as much as it could have been.

I've not heard a good solution, but it does not appear to have improved for the indicator in POE1 that has been questioned for years. Without looking at the math, I would assume with armour mitigation estimate of 37% at that level, a 1k+ phys hit is going to have close to 0 mitigation from that amount of armour. I'm at a similar part of the game in my HC playthrough, I got hit by slam and survived, but just barely. I was a few levels above the zone, because I knew it was a dangerous one shot boss. I had about 1.1k life and think my tool tip was about 45% for armour.

The Mighty Silverfist design itself I don't mind. Not withstanding your mechanical query, which I don't know much about, and will leave others to comment on. There are some mechanics on some of the campaign bosses, that seem rather HC unfriendly, if not following a guide. The Act2 final boss, wind ability, which you have to stand in a safe zone, that looks visually very similar to everything else, other than if you know to stand behind the NPC. I think the act3 poison boss also has a similarly dangerous mechanic that I noticed in my SC playthrough, but haven't made it up to yet in HC (Edit: Viper fight is actually a pretty good fight, other than it is hard to get chaos resistance at that point). They do need dangerous engaging mechanics, otherwise the game just becomes face tank everything. Overall, I think the campaign boss design and balance has been fairly good, other than a few mechanics like the one mentioned above, which I think is a bit of a gimmick.