So, first of all if we want to talk about ‘difficulty’ then we need to discern between the different types of that.
Thinking a single one is the ‘superior’ version to all the others generally leads to a bad awakening for a dev, unless it’s specifically tailored to a pretty niche amount of players on the market. For example ‘Super Meatboy’ is one such game, great execution, tight controls, no RNG. It’s 100% about dexterity by using your control scheme as perfectly as possible.
So, what is ‘difficulty’ hence split up into?
- Memorization through the numerical amount of mechanics during a fight.
In terms of the Julra fight she’s the hardest boss there. She has the most variety in mechanics provided in the game as much as I know. Puddles which need to position them, timeline switches because of her insta-kill explosion, invulnerable totems which you need to kill before switching timelines unless you can handle them becoming dangerous, a moving arena-reduction skill with her lasers and her personal attacks.
- Simultaneous numerical amount of mechanics to handle
This is how many mechanics are there at the same time. A boss which goes and changes between singular attacks one after another is generally easier then a boss which uses several at the same time. Julra here… once again… is one of the more taxing bosses, but the dungeon bosses in general focus very much on that aspect. You have permanent puddles, the lasers, totems and her personal attacks at the same time during the fight. That’s 4 things to handle at once.
- RNG factor
This is non-fixed patterns for example, for Julra those are few. We don’t have her chose her skills always in the same way. Sometimes you get totems first, sometimes her wave, sometimes she sets up the lasers first. RNG based difficulty is generally higher the more simultaneous skills are in effect at any given time since the decision making can’t be fixed and memorized but has to be situational.
- Reactionary difficulty
This is the part which depends solely on the player. In a competitive FPS it would be the reaction time plainly spoken. How quick does the player make a reaction as well as how ‘optimal’ is that reaction regarding to the situation?
This is not needed a lot of Julra, she’s a very mechanical fight and as long as you deal with her mechanics in the optimal way she poses very little of that.
The biggest reactionary things we see are actively dodging her personal attacks, the majority of her abilities are arena limiters meant to remove your mobility.
Your whole argumentation for ‘being good’ is the reactionary difficulty. That’s quite limiting… and also not the primary factor of most diablo-clones. Usually only needed for specific boss fights. Examples of where this is needed are for example Uber Elder in PoE as the RNG nature of Elder & Shaper working together demands you to react swiftly rather the memorizing the fight.
You’re not taking into consideration the memory aspect or the aspect of simultaneous ability usage at all. You’re declaring it as ‘a given’ from your standpoint. Which no, it isn’t for the majority of people.
Also your proclaimed problem relates solely to one game mechanic for her overall fight, one mechanic which - once again - can be entirely skipped so Julra uses it exactly ‘0’ times during the fight. Hence by that design death through the puddle is in 100% of cases a mistake from the player given the optimal amount of knowledge is there, hence knowing the way to ‘sidestep’ this mechanic.
So, which type of difficulty are you speaking there exactly? Because I spoke about the design aspect of Julra, which makes her the most complex boss mechanically, not reactionary. As mentioned before, I think reactionary the most taxing bosses in the game are Cremorus and The Mountain Beneath. Both of them have a more ‘frantic’ pacing then Julra but far less actual mechanics.
What more is needed? That’s a ton of EHP.