I have played through the game multiple times, so I do know what happens later in combat. I did a couple mock battles as well with the spider lair. 4 party, custom characters, strict 5e rules and stats for ettercaps and phase spiders. Well, matriarch and babies were of course fudged a bit since they have no genuine stats, but I gave them more reasonable 5e stats. Used Level 5 characters.
Again, tough battle. PCs almost died. Came down to Diadell finishing off the last phase babies. At LEVEL 5. So once again, the battle was kind of above normal challenge rating. Granted, it is supposed to be a boss battle, so that is more understandable.
It did work, though. It was balanced and challenging without cheese needed. It was also fun and exciting. I felt like it was nail biting. I was afraid the PCs were really going to get their butts kicked hard. That's how a boss battle should be.
I do think 6 PCs would make using the 5e ruleset more doable and balanced and fun for most battles. Fighting the spider lair would probably still be quite tough with 6 party members. Yes, it might be too easy with 6, but not necessarily. Bad dice rolls in that fight could quickly turn it in the DM save us direction just like in my Prologue example I wrote up. I almost had to have the Mind Flayer heal the PCs just so they could beat the imps and get to the helm.
But I think more players would prefer an easier gameplay for first time playthroughs, so allowing 6 PCs and strict 5e ruleset from pretty much start to finish would balance the game out better without cheese and allow players to have a bit more of a killing spree combat feel as opposed to dying and reloading a lot. I think most players would prefer that at least in their first pass at the game. Then, want a more challenging game? Play again with only 4 PCs. There's you difficulty settings right there. No need to do anything else. 6 PCs for Normal. 4 PCs for Hard. 2 PCs for Insane.
I guess what Im trying to say is I'd rather have it be too easy with 6 PCs but strict 5e rules than 4 PCs and lots of cheese rules needed to help keep them alive. I said it before. The 5e rules provide balance. The more you get away from them, the harder you have to work to compensate.
So it is better to rebalance by either increasing party size or decreasing enemy numbers and/or health. They do the health decrease to a certain degree with the imps in the Prologue, so that is something that I did not do for TT. Then again, I was trying to just prove that the 5e rules and stats CAN work just fine in BG3 as a cRPG. You don't need to cheese it. The game is doable and challenging and there are very few actual rules that would be difficult to implement in BG3.
