Since there is not an overall difficulty slider to 5e as there will be in BG3, how would you suggest making encounters easier and harder?
*Points to the difficulty settings in BG 1 & BG 2*
Use those. I mean this is supposed to be the third game in a trilogy, don't need to reinvent that wheel.
I don't think that will work in 5e. There isn't a way to out scale hits with AC like there was in 2e. BG1&2's main difference was more damage when hit but in 5e It's not even a matter of a completely min maxed character; you just aren't given the tools to prevent the hits, or guarantee them. You would just die from the increased damage on ever hit. I don't even think spell failure is in 5e, casting or copying scrolls, and that was another annoying trait of the difficulty slider.
What? There absolutely is...if Larian every decides to fix the litany of problems with their homebrew creations. Hell introduce the Dodge Action and right away you have the ability to minimize hits on your tank while your damage burns the enemies down/locks them down with CC. In BG 2, the highest difficulty settings (discounting SCS) were reserved for players with masterful knowledge of the rules *and* perfect knowledge of each encounter in the game. It's the difference between going into the Githyanki fight blind versus prepositing your team on the upper levels to push off the Gith and rain down fire on them. BG 1&2's highest difficulties weren't for players with more skills, they were for players with more knowledge *including* about the game itself. They weren't ever intended for players to use them on their very first playthrough, at least not without significant save scumming after learning the mechanics of a fight/enemy.
1. Max HP on level up vs rolled/average. Super easy to implement.
2. Incoming modifier. Again, super easy to implement and reserved for higher difficulties (winning fights before the enemy gets an Action)
3. Boost enemy AC/reduce player to-hit. Don't touch enemy HP, rewards players for proper fight prep and execution (again, largely requiring prior knowledge).
4. Introduce Arcana checks to scribe spells (risks losing GP on failure and destroys scroll)
5. Disable enemy critical hits
6. Remove/enable perma death absent rules based options (no revivify scrolls at the beginning, enable/disable death saves, etc).
Seriously, just do the 5e retrofit of the original series' difficulty setting. Ideally, then introduce SCS changes for the ultra-hard modes that actually increases enemy AI/behavior/spell choice, etc.