TheBear

I like the idea, from what I can see the mana probably needs some work, I would only run 1-2 fairs, being legendary can be an issue. A d to help with the double black spells I would probably play a second urborg, and I don't think you even need the mountain if you have a Blood Crypt.

If you want to go further on the pox style, you could play some number of Death Cloud, but I would recommend playing some signets over the mox Opals in that case, Metalcraft can be hard to get early in the game and being non-legendary helps with ramping into huge cloud turns.

Cutable cards could be the Welding Jar, Batterskull and actually Thirst for Knowledge, I think you can play more utility artifacts like Trading Post, Walking Ballista, an extra Aethergrid etc. I've never been a huge fan of thirst in these decks, it's felt clunky. Jar seems a bit low powered, and if you cut mox then the assistance for metalwork isn't as needed. Batterskull I just like the idea of little to no creatures or attacking to maximize bridge and Smallpox.

I'm actually not a fan of Renegade Rallier in this list, without feth lands it seems very difficult to trigger Revolt, the rest of the list looks solid otherwise, I think I would max out of Thalia, guardian of thraben, ND even think about playing Thalia, heretic Cathar, she's been impressive in lists I've seen her in.

Loxodon Smiter might also be a good option to play.
Dryad militant would be a very good 1 cmc creature, really good at screwing with Snapcaster Mage.

Feels a bit too threat light, I would want Monastery Swiftspears, Stormchaser Mage and possibly even Thing in the Ice.

Also instead of the 2 mana burn spells, why not just Lava Spike or something like Rift Bolt.

It was probably required, gave it the strongest draws and also a late game of just casting giant trolls.

I think being just basics is not much of a limitation, you already play 7 basics, you could cut the Urborg for another Swamp, then maybe you can trim on a Drownyard Temple for another basic.

I lied, not BFZ. It's a Shadows card, Groundskeeper. Just a 1 drop with 2 mana return a basic from grave to hand.

(Noting this first, I don't play Frontier or am familiar with the format, so I'll try my best to be useful just out of deck construction and synergy)

First, I don't think you need Aggressive Mining, I understand the value combo with Splendid, but I think cutting you off of playing Lands seems dangerous paired with Gitrog in some situations.

If anything, I would prefer to play stuff like Kolaghan's Command over Pulse of Murasa (Doesn't recur Lands but it's a more powerful effect in my eyes) Maybe go to 4x Vortex. The other idea would be to look if there is any cards that return lands to your hand in particular, that would generate and engine without being as clunky. (I believe there was a 2drop in the BFZ block that could do this, I can't remember the name at the moment)

I would also recommend some kind of removal, it's always useful to have other then Vortex which would be difficult to get enough damage to kill something like a Siege Rhino or Atarka. (I believe they are legal in this format, but I bet there is other fatties also)

I think it might just be better to cut the Stirrings and go straight R/B, I don't think it's worth stretching the mana to incorporate it especially with the mass of colored spells giving you a lot more potential to miss unlike the Bant version

Have you tried the version of Shardless using 1-2 Leovolds yet? Been hearing positive things about him recently.

This is who you think it is.

I like the idea, but I think you can push this idea further.

First off, there was a deck a while ago called Eternal Command, it would use Aether Vial to put Eternal Witness into play for free, use her ETB to recur a Cryptic Command from grave to hand, and then use that Cryptic to counter a spell and bounce the Witness to hand. Causing a loop of counterspells and value. I feel like it would be worth fitting that into this deck.

Next, I really don't think this is a Steel Overseer deck, you want him if you would go wide with artifacts like in affinity. The same goes for Skite, it's good but not something required I think if paired with enough countermagic and potentially Eternal Witness recursion.

Next I would probably trim one Ancestral Vision, it's good but not a four of good in my opinion. And Collected Company, you don't need to use it to generate advantage, feels a bit like a win more.

Cards I would want in here would be that Eternal Command package with Witness and Cryptic Command, with that I would up to 4 Snapcasters to fully abuse it.

Puschkin's hit the nail on the head perfectly I think.

Just a tad confused, before I start recommending ideas.
Is this meant to be a legacy list, or modern with just cloudpost, because they are banned.

Which is fair, I just feel it's best to maximize on the cards that have the synergy with each other.

I like the idea, an eldrazi rock hybrid kind of deck, I feel like some of the numbers are wrong though.

For eldrazi to work, and your Caverns+scourge value to work. You really should play the full playset of Temples and Caverns, and to help with mana, Llanowar wastes and Cavern of Souls are great options.

Next, if you really want Chalice to work, go to 4x, then cut all the 1 cmc spells. Go with cards like Collective Brutality to cover for lack of Thoughtseize, play a fourth Scavenging Ooze to cover for Relics, etc.

Bring up to mana to about 23-24, and play the max of Eldrazi creatures such as Matter Reshaper and Reality Smasher, they are your best grindy and powerful threats.

I feel like this deck could really appreciate some form of ramp, something along the lines of Sakura Tribe Elder or Search for tomorrow, your plan is to cast a 4cmc spell in gifts and 5 in Bring to light, which I think should be more then a 1x, considering the toolbox aspect of the Deck.

I like how the MB is looking right now, two small things I think you would like to have though.
Academy Ruins, it works very well with the Thopter/Sword combo, as a way to get one or the other back, and it also seems disgusting with Torrential Gearhulk as a way to recur it.

I would also recommend playing Collective Brutality, maybe with some number of Lingering Souls. The biggest weakness I've found with Esper is a lack of good early removal other then Path To Exile. Brutality fills the role very well and also doubles as hand disruption. Lingering Souls is just so you get value from pitching cards if needed.

If you want to be closer to the Legacy version of Merfolk, I would recommend playing 1-2 Umezawa's Jitte and a playset of Chalice Of The Void. Jitte is one of the best cards for opposing creature decks, and Chalice helps you further against the unfair decks, you also play very few 1 drops so it's not too restrictive.

I would also recommend a playset of Wastelands in the main.

For the sideboard, it feels too Modern Format styled. I would want grave hate, stuff like Grafdigger's Cage and Relic of Projenitus is a must. You could also play stuff like Back To Basics, Hydroblast/Blue Elemental Blast and Spell Pierce to help against Combo and more Midrange decks.

Adding green does very little to this style of deck, the Cantrip alone isn't worth it. Instead of Hedron Crawlers I would just want to fill out the playsets of Displacer and another Smasher.

And about Blessed Alliance, it does fill a specific role in this kind of deck. Lightning Helix is probably too much for the manabase to handle, Alliance is the only other option. Lifegain and removal. Even it's untap clause is very effective with the mass of creatures.

And he's already playing a playset of Path To Exile, Boros Charm does extremely little in this kind of deck. (Indestructible being maybe the only valuable effect, maybe the double strike, but not enough to warrant inclusion.)

... Alright, that actually makes it more difficult.

Alright, so the only ways if you want to make Demons viable, is (Maybe?) Using Shadowborn Apostle as a way to cheat them into play. There isn't any real efficient way to ramp them out or cheat them into play unless you are willing to pay alot of cash for stuff like Show and Tell etc.

For Maralen though, I have seen her in B/W Hate Bears, when paired with Leonin Arbiter and Aven Mindcensor, limiting your opponents searches or even denying their searches in general.