5E will have to provide some way to handle the psionic attacks of the Illithids. Thinking back to BG II and Throne of Bhaal, I wonder if something more could be done to make psychic combat more visual and interactive? In BG II, the Mind Flayers sort of just wave their tentacles at you, and then bad things start to happen and you die pretty quickly unless you have an immunity item, in which case you can then mow them down without too much trouble.
AD&D had lots of different types of psionic attacks (Id Insinuation, Mind Thrust, Ego Whip, etc.), and I believe they all happened very quickly relative to physical combat. I wonder if the Larian game designers might make some occasional psionic-only vignettes, where the player can actually "see" what goes on during these attacks, and choose defenses and counter moves just like in normal combat?
"All the scars are on the inside ..."