Casters don't need buffs. Martials and consumables need nerfs. Too many extra attacks, venoms are broken, and so are speed potions. Martials also got like three to four times the item pool the other classes did, including like 5x the amount of legendary weapons.
Druids and rangers are the worst class, with bard after. Those could use a few touch ups, but in general bosses are dying too quickly because speed potions and venoms and multiclass extra attack perks are giving too much power creep to martials and some casters.
Lore Bards are hilariously overpowered. Take one and only two enemies in the entire game ever gets to do anything ever again. I'd say it takes two and a half wizards to compare to a lore bard in terms of power.
Otto's needs a nerf, I've said it elsewhere. The issue is that Ottos scrolls are available like candy by Act 3, so their unique brand of OP is easily replaced whereas a Fighter, Paladin, or Monk have no substitutes. Martials can do what casters can with scrolls because Larian for some reason allows them to benefit from scrolls on top of having all venoms, oils, and potions disproportionately benefit them. All a caster has to look forward to in an elixir is an extra spell slot, and a lv4 spell slot at best. It's so stupid how martial-favored this game is.
Bosses should have an innate that gives them strong DR to CC effects so you can't just stunlock them to death, and autocrit on paralysis needs to go.
Every single strategy in this game is drink a speed potion and burst a boss down in 1-2 turns with 4-6 autoattacks. Oh, and we put in a bunch of items that increase attack rolls and some gloves that set the STR to 23 in case it wasn't obvious we want your autoattacks which cost zero resources to hit for 50-70+ a piece and require no long rests to replenish.