Got smashed again at Wednesday Night Magic today. Lost three rounds but at least I managed to win 2 games for a 2-6 record today (from 0-6 on Monday night which was where I played my first Standard game ever) so I'll take that at least. My third round was a mirror match against another Esper Control and I lost to 2 Mutavaults. I don't run any Mutavaults in my deck but I am heavily considering it now. Also thinking of running 1 or 2 Ashiok in my main deck. Finally, I am also thinking of switching to UW Control but that would definitely require 2-4 Mutavaults and I'm not sure if I want to buy that so close to rotation.
It's a trap. It's more that Esper is a hard deck to play as your first Standard deck. You're going to lose more games from having uncastable cards and Mutavault than you will win them because you could block a couple times. UW gets 4 mutavaults because they play 2 colors and run garbage cards like Azorius Charm and Divination to get them to double white or blue on turn 4.
Ashiok is a good card, but it's a slightly different Esper build and you have to readjust the whole structure to play where you're tapping out most turns. Generally it means a harder black splash and some better cards mainboard. It might also mean you can't afford to run as many counter spells.
The reasons to run atypical cards like Ashiok and Brimaz are meta calls that benefit people who really understand the sequencing of plays in different matchups.
For instance, in a regular Esper mirror, you can tap out on turn 4 on the draw for Jace because your opponent isn't going to have anything major to threaten you on the crackback. But if your opponent is running cards like Brimaz or Ashiok or Memory Adept that see fringe play, it's a huge blowout that can lose you the game. You have to tap out to sphere or verdict within a few turns, which lets your opponent resolve another win condition like Elspeth or AEtherling.
Playing cards like Ashiok can also mean you can afford a harder black splash that gives you access to cards like Hero's Downfall that make you more dangerous against midrange and control matchups. But the rough manabase can also mean you have unwinnable game 1 matches against a deck like burn that doesn't care about your removal or planeswalkers.
I been outta the game 2 long, brehs. What are the strong cards in grixis in the current standard cycle? I must control.
Stormbreath Dragon
Desecration Demon
Hero's Downfall
Thoughtseize
Rakdos' Returm
Ashiok
Jace, Architect of Thought
Dissolve
Syncopate
Pack Rat
Nightveil Specter
Cyclonic Rift
Underworld Connections
Mizzium Mortars
Chandra Pyromaster
Liliana Vess
Aetherspouts
Slaughter Games
Sire of Insanity
A midrangey Grixis-control build is totally possible.