5th edition specifies a number of powers that that while mental based, bypass Mental Defense. Examples include Entangle BOECV and Flash vs. Mental Senses.
This is overruled. Mental Defense is applied to any power brought with BOECV (although resistance for Mental Defense may need to be purchased for defense vs. killing attacks). It is also applied to Flash vs. Mental Senses.
With respect to Mental Entangles, the character with such defenses gain 1 point of EGO per point of Mental Defense for break out attempts. Characters attacked by a Mental Entangle get a immediate and free breakout action using their EGO (plus Mental Defense).