If you really tried? If dedicated yourself to anti-Shops anti-MentorCantrips?
So i don't totally know what i am doing, but i was brewing around (on paper) and came up with something like this. This is an excercise and thought experiment but i'm not not serious about making a real valid attempt at making this as viable as possible. It may be garbage, and if so, it may be unsalvageable, but we don't build decks for no reason so there should always be something to learn.
Creatures: (18) 4 Deathrite Shaman 3 Dark Confidant 3 Grim Flayer 1 Gaddock Teeg 2 Sulfur Elemental 1 Dryad Arbor 1 Manglehorn 3 Ramunap Excavator Hand Disruption: (10) 3 Thoughtseize 2 Inquisition of Kozilek 2 Chains of Mephistopheles 3 Liliana of the Veil Removal: (8) 2 Abrupt Decay 1 Abrade 2 Ingot Chewer 2 Sudden Shock 1 Snuff Out Tutors: (4) 1 Demonic Tutor 1 Vampiric Tutor 2 Green Sun's Zenith Mana: (20) 5 Lotus, Sol Ring, Moxes 2 Bayou 2 Badlands 1 Taiga 3 Wasteland 1 Strip Mine 3 Verdant Catacombs 3 Wooded Foothills
The goal here is to get ahead in mana with the set of 4x Deathrite Shaman and 1x Dryad Arbor, which is fetchable with 2x Green Sun's Zenith.
Dark Confidant provides card advantage that dodges Chains, and while i have 34 cards at 0-1 mana, i have a lot of 3-mana spells. He dodges damage with support provided by the filtering Grim Flayer can provide, who can attain Delirium by himself, but i have a fair amount of various spells and sac-lands to get him there.
Flayer also pitches lands for Ramunap Excavator so i can draw actionable spells when i want and play from my 'second hand' for lands. Ramunap provides further support against Shop's Spheres and Wastelands, and i hope also provides me a Crucible to win those attrition wars since it seems Shops is not on Crucible.
There's some Sulfur Elemental for White Weenies and some awful temple-dwelling spiritualist that makes terrible 1/1s. The elemental is not totally terrible vs non-white decks, as he still is an uncounterable 3 power flash dude and knocks Jace flat.
Teeg and Manglehorn are extra flex for Green Sun. I'm not sure about Manglehorn on the whole. He sure does come down and poop on a Shops piece, but i also thought it stops some Fleetweel or if get the drop on Paradoxical he can stuff them up. Teeg works against Paradoxical, the spell, as well Force and Jace. Stops me from Casting Snuff out and of course Green Sun but that is acceptable.
The one-for-one 1cmc hand disruption is really sad against Mental Misstep, no doubt. Which is still marginally useful as it's easier to cast some Deathrites later perhaps. It is, however, generally perfectly acceptable against forms of combo still.
Chains is in there because of cantrips/JaceDack galore and variants of Paradoxical and maybe sometimes Griselbrand out of Oath, with some splash against metalcrafting Thoughtcast types.
Liliana is not the threat she is in Legacy, but she is still too good to not be an autoinclude if you are playing BRG grind. She may not be as scary as mentor and she does not destroy mentor, but Liliana lets you pitch lands for later use with Ramunap (you don't play your land drop from hand) and activate Flayer much easier, and if you get to grind for 2-3 turns against a blue deck, that feels just swell. She is very reasonable vs Oath if she can resolve, but that is not especially likely i feel, and doubly doubtful if they are on Griselbrand. She's garbage against shops because of their threat density/Precursor, Revoker, Ballista, and Hangarback.
The removal suite is built clearly around Monastery and artifacts. I tried to diversify very well against other decks.
2x Abrupt and 2x Sudden Shock give serious edge vs Mentor, although with Abrupt they may possibly get tokens instead of 1. I mean they can even 'counter' targeting Abrupt. Abrupt is also just regular amounts of powerful vs many things as a catchall. Dack, JVP, Oath, most creatures out of Shops even if not ideal, Paradoxical stuff.
Sudden Shock seems like such a Mentor card of course, but also can lay some serious damage against Shops. It may not seem like much with the two damage, but not only does it kill Revoker, it can destroy Ravager or Ballista before any activations or in response to an activation maybe targeting Factory. It can be played around, but maybe you poop on someone's day for a minute when they don't think you are playing such a thing.
Abrade is some serious flex i think. Mentor may dodge it if they are holding two spells, and it can be countered as normal. But it will kill it sometimes, so it's not totally dead, even though it shines a little more against shops, and of course has a splash against Paradoxical stuff and the few fair decks like Maybe a Leovold.
Grudge and Nature's Claim are just more diversification. Grudge is very specific and narrow but can be cast twice, which i value, and has bonus points for pitching cleanly to Lili or Flayer.
Snuff out is just fine as yet another removal vs normies, but 'free' casting against resisters in Shops makes this flexible there, and it also kills Eldrazi as well as dodge their Sphere a little.
Demonic and Vampiric just help along the way of a little card selection with the silver bullets, or helping ensure drawing Ramunap or the correct removal.
Green Sun's has more than enough targets to be fine to draw later in the game. It's got 2 silver bullet types but the standard engine-guys of Ramunap, Deathrite, and Flayer are there.
Mana is some standard restricted artifacts, regular duals and fetches, but also a set of Wastelands for grinding and taking out Shop, Bazaar, Academy, Library. I didn't set on any basic lands or go over 5 colored mana producing lands, and i do not know if that is correct. I want some number of fetches, but they are not great with Ramunap after you have pulled out your 'real' lands. It may be more correct to drop a fetch and something else for a couple extra 'real' lands, but it is also possibly very incorrect to do since Deathrite wants some lands to eat. Without a lot of practice, i cannot say right now that Deathrites are going to get there on the mana. They can Misstep, Plowed, or Revokered and absolutely none of that garbage is what we want.
I believe the sideboard includes a couple Sudden Shock and Ingot Chewers to replace each other when you find out which deck you are playing. There is the rest of the typical stuff, and some things like Tormod's Crypt are also sweet for a boost to Flayer.