Right now, going through ToB for the first time in a decade, I'm playing Ascension with SCS improved bosses. I've just encountered Draconis, who has apparently sixty Improved Invisibility spells and has summoned about twenty invisible stalkers.
Next, I encounter Abazigal. Or rather, Abazigal encounters me, along with five wyverns with all manner of bizarre traits like permanent level draining attacks, stoneskin and invisibility, and a dragon who is, against all logic, not only immune to imprisonment but if targeted by it becomes immortal (to my forced reloading disappointment). Abazigal himself of course heals and polymorphs into a dragon when you defeat his human form, is immune to time stop, casts every spell instantly, and automatically casts Remove Magic and Silence via script time and time again, and the lot of them automatically charge you the moment you enter, so you'd better hope you knew that ahead of time and pre-buffed.
In a way, that's fair enough, the fights are still very much winnable and are certainly challenging, but at the same time, the way it's accomplished is... Unsatisfying to me.
In fact, so much of SCS's "upgrades" feel that way to me. The game is build around universal rules, and when those rules only apply to the player, it very quickly takes my immersion away.
Every single thief carries around half a dozen potions of invisibility? You know how much that would cost? How are they supposed to make a profit if that's how they handle every fight? It's bad enough that invisibility instantly detargets even though it's not like they moved yet, but doing nothing but spam the ability? That's either unbearably deadly or unbearably tedious, depending on whether you have true sight and stoneskins.
Mages reset into full buffs whenever you see them (including if they happen to go out of sight for half a second while you duck behind a corner to heal or hide)? Where are they getting all these spell slots? Why don't I instantly pop out long lists of instant pre-buffs right before every combat even though I was previously in the middle of dinner?
Why can't I have a bunch of Protection from Magical Weapons spells that automatically activate whenever's (in)convenient, and why, oh why, can't I be immune to Imprisonment with no preparations and no excuses?
But so many "enhanced" combats appear to be predicated around this idea of the player running on different rules to everyone else. Illasera vanishes and turns ethereal at will, Yaga Shura is pretty much immune to non-poison damage. Wyverns with energy draining attacks like vampires, dragons which spam remove magic so often they might as well be Beholders...
Is this necessary?
I think of Firkraag's dungeon, where you enter a room and orcish archers are shooting you from all sides, forcing you to search out the secret doors to their hideout while trying to return fire with your own missiles.
I think of Firkraag himself, a hugely powerful attacker with defences that make most players scratch their heads when they first encounter him. And the vampire lair, where you're forced to marshal your resources around anyone you can protect from level drain as you struggle through some nasty fights towards Bodhi.
I even think of some of the good parts that EE has introduced, some fights I found plenty challenging without any obvious rule-breaking (Neera's ToB questline in particular provided one of the most entertaining fights I've had in the whole expansion), and a fight that did break the rules with a completely unkillable NPC attacking you, but in a way that felt dramatic and fulfilling as you were forced to escape, and that part didn't feel cheap, because it was well justified by the plot, wasn't obviously arbitrary about it, and helped move the quest along to a dramatic conclusion.
What are your feelings about introducing difficulty by breaking the rules? Can an encounter follow the rules of D&D, maintain the integrity of the world it simulates, and still be a challenging, enjoyable fight for experienced players, even at the peak of their power? Could simple tactics and scenario features provide difficulty even to a player who has faced that scenario before? What techniques would you be interested in seeing to make a fun, memorable and challenging encounter?