And yes, in terms of phase spiders, when you first encounter them in the original games, you are walking through a dark cave system and they suddenly appear around your characters attacking them at point blank range. They hide in the ethereal plane and then pop into the material plane to attack you. While in the material plane, you have maybe an attack or two before they will attack you again and then go back to the Ethereal plane. Then they'll suddenly maneuver behind you and pop back into the material plane and attack you again. Then you get like one round to hit them again before they go back to the Ethereal plane. That is how they are supposed to be. They are hit and fade assassins. They don't Misty Step across the board some 120 ft away from you and then spit poison at you.
