Well,back to topic....there is something off about tartarus's plan.
Isn't Zeref a mage? Why activate face if Zeref too will lose his magic.Then,I remember what Zeref said that only natsu or E.N.D will be reaching him...I am led to believe that E.N.D is using Tartarus's blind obedience to Zeref in order to kill him.
What is really off is that E.N.D hasn't graced us with his presence.It doesn't even look like he is on Cube either. It is also quite odd is Igneel going after him to kill him,then letting E.N.D live.
Hope E.N.D shows up on a possible part 3 after chapter 377...If the prologue had 8 chapters,and part 1 had 7 chapters,part 2 will probably have 7-8 chapters as well.
That could explain why Zeref refuses to show himself to Tartarus,even though they are going through so many hoops in order to meet him.