I built and played a HollowVine variant for the recent Team Serious Invitational and finished in 2nd. I went 5-0 (no draws) in the Swiss, and lost in the finals to a player I beat earlier in the day. I couldn't be happier with the list. Working on this deck has been a ton of fun ... it forces you to think about the game in a way that's less traditionally Vintagey, it kind of uses Dredge reasoning to do non-Dredge things, and I think an experience Standard aggro player would get a kick out of it.
It does one of two things, it does them on the first turn, and it does them very consistently. Bazaar of Baghdad can put a 4/x (Hollow One/Vengevine) into play, or artifact mana/Elvish Spirit Guide will put a hate-bear (Thalia, Guardian of Thraben/Collector Ouphe) into play. Often both.
On reflection, I believe this is a Sligh deck. Not in the sense that it's aggressive, but that it's a deck that was willing to run Brass Man because having a one-drop was more important than having a not-terrible card. I'll get more into that below.
Here's the decklist, with a built in primer:
2nd Place: Andy Probasco
Play a hatebear
Attack for 4
Follow up with
Here's how I sideboarded:
-4 Stonecoil Wurm
-2 Deathrite Shaman
-1 Strip Mine
+4 Mindbreak Trap
+4 Force of Vigor
-1 Thorn of Amethyst
-1 Chalice of the Void
-4 Thalia, Guardian of Thraben
+4 Force of Vigor
+2 Kataki, War's Wage
+3 Leyline of the Void
+2 Surgical Extraction
-4 Collector Ouphe
-1 Chalice of the Void
Personal opinion, of course, but I think the use of hatebears is an upgrade (side-grade?) over other hate packages. I won a third to half of my games without active Bazaar, and I feel that if I had pitch counters or Spheres over Thalia/Ouphe, I would have slowed my opponent down more effectively, but given them more than enough time to comeback from it. Thalis and Ouphes triggering Vengevines is also pretty significant. I do think that the counters/spheres are better disruption if you already have a strong hand without them.
The **Outcome ** matchup feels very good, despite being my one loss. No matchup feels particularly bad in the way that Shops v Outcome does. I think you can build a reasonable deck that's very favorable against this, but there aren't metagame incentives to do that right now. I was most afraid of BUG with Tarmogoyf and Tabernacle, but I beat them 2-0.
The weakest card in the deck was Stonecoil Wurm, which I ran over Memnite because I wanted a way to kill Bridge from Below against Dredge. I'm not sure if there's a minimum number of free creatures you need to run to make the deck work - bad free creatures might be a necessary evil.
Surgical Extractions are a nod to the TSI metagame where Survival is more likely than Dredge. I'd probably run more dedicated Dredge hate in the Champs metagame, but so far I've been very favorable against the deck despite not dedicating many cards to it.
Kataki, War's Wage is very bad against Walking Ballista. I thought that the Collector Ouphes would make it better, but I'm not sure that they do. It's really nice in that matchup to have your hate card be a 1W creature, but I'm not sure it's correct.
Once the deck stalls out, it's very unlikely to recover, creatures such as Tarmogoyf that can block a 4/x are very scary, though in practice I've been able to pressure fast enough to force my opponent into bad attacks or blocks. I have this weird feeling that the Exalted trigger on a Noble Hierarch could be really effective against opposing Lhurgoyfs/Constructs/Eldrazi, but with the deck as it is there just isn't much use for the mana, and maybe a Path to Exile would be better.
It doesn't use the graveyard as much as you think. It doesn't use the graveyard as much as your opponents think. People see Bazaar and Panic but there's just 4 Vengevines in the list and I'm not sure Tormod's Crypt is any more effective than a Swords to Plowshares. I do think perhaps there's some opportunity to run a few more graveyard-centric cards and I want to try Ox of Agonas in this
Once Upon a Time is really good. It's probably great in Survival and solid in Dredge. I have a lot of thoughts about it, some unintuitive. People see the card as a way to find Bazaar more consistently, but in a Bazaar reliant deck, you can't keep an opening hand that has OuaT and no Bazaar. The card is at its best in a hand that can be greatly improved by a specific Land/Creature, but still has plays if you miss. In that sense I think that this list is one of the best homes for the card, but it's excellent in Survival as well (maybe better). This deck just just need Bazaar, it has a ton of hands that need one particular piece to take them over the edge and Once Upon a Time gets all of them. It gets Vengevine to make your Bazaars better and Basking Rootwalla to make your Vengevines better. It gets Collector Ouphe to shut your opponent down and Elvish Spirit Guide to cast it on turn one. It finds Strip Mine and your opponent groans. I believe I found literally every creature in my deck with OuAT at least one time during the event.
This is maybe the most aggressively mulligan'ing deck I've played, even moreso than Dredge because I'll happily Serum Powder a hand with Bazaar in it. I did more than once and didn't lose those games. On camera I Powdered three times and opened with Bazaar which means I saw literally 30 cards before either player played their first spell.
I think there are some properties of this deck that might not be clear just looking at the list. The combination of Serum Powder/Once Upon A Time/Bazaar of Baghdad compresses your possible opening hands, which makes some lines more common or relevant than they look. Some of your hands are going to be Bazaar hands where other cards don't matter so much. To speak in specifics ... a deck with 4 Elvish Spirit Guide and a bunch of 2 drop HateBears is one of the oldest archetypes in vintage and it's never been particularly dominant, and certainly isn't seen as a "raw power" deck. HateBears are slow most of the time and 4 ESGs isn't enough to consistently play them turn one. This deck isn't any more likely than those decks to have a turn 1 Thalia in a random 7 card hand ... but there is a key difference.
The 7 card hands that go "turn 1 land, ESG, Thalia, turn 2 land Ouphe" are just as common as they were in any other aggro bears deck. Those hands are strong in HateBears and they're strong in HollowBears. The flaw in HateBears is that those hands aren't common enough, and the other possible hands are very weak. Once Upon a Time improves both decks, making those hands more likely. But with HollowBears, some large portion of the hands that don't have that opening, have a strong Bazaar opener instead. But if you don't have either your chance of having a Serum Powder in those remaining cards is much much higher, and Powder is extra strong in that scenario.
The end result is that you see a manabase that looks like manabases you've seen before, but in practice the amount of games you play turn 1 lock piece is much higher than the amount of games you play one on turn 2.
Because of this effect, which honestly I'm having a hard time articulating ... the entire design of this deck is pushed toward your opening hand, and choosing which cards to run seems to be more about crafting a turn 1/turn 2 sequence which work together than it is about finding cards that are particularly good.