Ok. This is driving me crazy. Use true D&D stats and stop nerfing enemies. I mean, BG3 is balanced fairly well right now but only because monsters aren't really genuine. A Mud Mephit should have more health and it gets only a 25% chance of multiplying and it should be hidden as mud to begin with. A Phase Spider should use Ethereal Jaunt to phase out of and into the material plane as a Bonus action, not teleport and spit but melee range. Intellect devourers should use Intellect Devour, one of their main attacks, and they and imps shoyld be resistant to different attacks.
Larian is taking some aspects of these monsters but not all. Why? Instead, why not allow bigger party size, less enemies and maybe even enemies that fit the encounter more. Im trying to play out these scenarios via Tabletop, and they are BRUTAL. 2 Mud Mephits and 2 Wood Woads is too much even for 4 Level 4 characters.