I think if I wanted to play rough and didn't want to go completely broke, I'd try something like this. The pure combo builds are probably better in cEDH, but a lot of times their mana bases are crushingly expensive. Lavinia is pretty good though -- she's a cheap hate bear who hard answers some of the better combos available, and with Omen Machine or Knowledge Pool she locks down the table.

General
Lavinia, Azorius Renegade

Creatures
Trinket Mage
Tribute Mage
Spellseeker
Aven Mindcensor
Phyrexian Revoker
Ethersworn Canonist
Containment Priest

Mana Rocks
Sol Ring
Mana Crypt
Mana Vault
Chrome Mox
Mox Amber
Azorius Signet
Talisman of Progress
Fellwar Stone
Mind Stone
Gilded Lotus

Other Artifacts
Isochron Scepter
Grafdigger's Cage
Sensei's Divining Top
Knowledge Pool
Omen Machine
Cursed Totem
Voltaic Key
Torpor Orb

Enchants
Blind Obedience
Rest in Peace
Aura of Silence
Land Tax
Back to Basics

Tutor/Cantrip
Enlightened Tutor
Mystical Tutor
Fabricate
Merchant Scroll
Ponder
Preordain
Brainstorm
Omen

Instants
Counterspell
Dovin's Veto
Negate
Force of Will
Force of Negation
Muddle the Mixture
Mental Misstep
Path to Exile
Swords to Plowshares
Dramatic Reversal
Stifle
Flusterstorm
Honor the Fallen
Reality Shift
Abolish
Disenchant
Whir of Invention
Dispel
Blue Sun's Zenith

Sorceries
Wrath of God
Supreme Verdict
Terminus
Day's Undoing
Windfall

Planeswalkers
Narset, Parter of Veils
Teferi, Time Raveler
Tezzeret the Seeker

Lands
Ancient Tomb
Hallowed Fountain
Seachrome Coast
Prairie Stream
Glacial Fortress
Sea of Clouds
+ basics

Besides the Lavinia locks, the other win-con for the deck is Isochron Scepter + Dramatic Reversal. With enough mana rocks in play (ie, can tap for 3 or more mana), you have infinite mana and infinite untaps. If you also have Sensei's Divining Top in play, that turns into infinite card draw (tap Top, then respond by activating Scepter, then tap Top, etc). Or if you have Blind Obedience in play and you can make infinite white mana, you just win (Each Dramatic Reversal copy triggers Extort, life drain the table to death).

This list is only mostly expensive (~$730 on tcgplayer), although I didn't include pretty good cards... Mana Drain, Scroll Rack, and Time Spiral would make the deck MUCH better. You could also double down on the infinite mana loops with the monoliths, Rings of Brighthearth, Power Artifact, Staff of Domination (and maybe throw in a Transmute Artifact).

Lands are basically a bottomless money pit, but they wouldn't contribute as much here as in some other builds, since you probably want to get Back to Basics into play.

Nice build, it seems like it could work well on a budget. Lavinia is fun to play, even though her stax locks can be annoying they aren't impossible to play around/against.

Some suggestions, I think you may have one too many wraths. I would cut one for Swan Song or Mana Leak. Also are there a lot of reanimator decks in your meta? There is a lot of grave hate in there.

Overall looks fun, I have thought about making a Lavinia deck before just because everyone in my group likes rocks. If I ever do maybe I'll come back to this list.

Thanks! ...and I agree with most of your points. With a couple extra high money cards, you could definitely trim a few extraneous pieces: a wrath (probably Terminus), Voltaic Key, an artifact removal, and Torpor Orb could all be swapped out.

The best counterspell to swap is obviously Mana Drain, but my favorite budget option would probably be Disrupt. Mana Leak is fine, but I don't actually like Swan Song very much... Narset and Teferi are really good, and I wouldn't want them murdered by a bird token (which is embarrassingly hard to get rid of).

I like the extra graveyard hate, partly because my friends like Gitrog Monster and Hermit Druid. I think it's a good choice for an unknown meta too, since Protean Hulk and other graveyard shenanigans are popular options. I think Honor the Fallen is a bit of a hidden gem... it's an excellent ambush card, and it gives you an anti-GY option that's tutorable with a spell tutor. But again, if you were going to invest a lot more into the deck, it could be replaced.

Oof Hermit Druid and Gitrog together is a rough meta. Grave hate away!

I get what you're saying about Swan Song. I have lost walkers to swans before in my Feign Veil Teferi deck and it feels so bad.

This seems like a pretty reasonable (budget) high power list, but I gotta ask what that Days' Undoing is doing for you. As a hatebear/stax deck, giving your opponents more cards at the cost of your turn seems pretty bad (assuming you don't have a hardlock, but if you have a hardlock they should probably scoop).

No Treasure Mage for Knowledge Pool and Omen Machine? Do you feel the reveal gives up too much information?

Edit: Sea of Clouds for Seachrome Coast?

This looks right up my alley. There are a couple big ticket cards I just won’t be able so afford, but I think I may steal the bones.

It might be too cute, but Lavinia breaks the symmetry of Dream Halls.

@HoffOccultist: A few handy Day's Undoing plays --

1. 'Walker synergy: With Narset, you draw, they don't. With Teferi, you can Days on someone else's turn.
2. Extra explosive starts: With fast mana and cheap stax pieces, sometimes the deck dumps its hand early before opponents can do the same. When you Days, you net 4-5 cards; opponents might only net 1-2.
3. Yet another anti-GY card: It's not the best, but sometimes that's still good enough
4. Everyone topdecks! This is a fringe play, but if you have Omen Machine without Lavinia, you can Days to kill everyone's cards and put the table in topdeck mode.

Admittedly, the Timetwistereffects are better in multiples, so Days Undoing gets a lot better if you also have Time Spiral and the original. Time Reversal and Commit // Memory might be reasonable adds if you wanted to play a more 'twister loop style build.

@Spectrar:

I don't know if you really need Treasure Mage. The deck's pretty slow, so with its current tutors/cantrips you have a good chance of finding one or the other by the time you need it. The other two mages make the cut 'cause there are a lot of different early-to-mid game plays to make with them.

I blanked of Sea of Clouds. I'll edit it in.

@kirkusjones

Wow, that's really clever. I can't believe I didn't think of that... a friend and I were just talking about things you could do with Painter's Servant and Dream Halls. I don't know that it fits with this list exactly... maybe Lavinia + Dream Halls is the build with all of the Timetwisters, and you just play through your entire library repeatedly.

I mean, I know what it does in general. I just think you probably could find something with less of a drawback than that to fill the slot. Heck, I'd rather run something like Time Spiral over it--though, honestly, I'm not sure that wheels in general are what you want to be doing with Lavinia at the helm. Narset makes them better, but I'd rather have another stax piece there or something.

Yeah, that's fair. I said upfront this was a theorycraft deck... it could all be terrible

(I think probably not, since it's an-already-pretty-good Grand Arbiter Augustin deck that I'm pretty sure got a lot better with Ravnica 3 cards. It could still be terrible.)

But Narset, Parter of Veils is low-key one of the most powerful cards printed in a long time, and I think if you can fit her into a deck, you probably should. Even without a few Windfalls, I'd still rather have her than another stax piece. She's already an asymmetric Spirit of the Labyrinth, and getting some cantrips along the way is pretty sweet.

Also, Time Spiral's a $70-80 card at this point, so if you want the effect but already broke the bank on Mana Crypt and Force of Will, Day's Undoing's probably your third-best option.

What are people’s thoughts about Snow Basics + Marit Lage’s Slumber as a win con that can come down before the lock and activate after? Otherwise the deck seems light on ways to actually win, outside of Dramatic Scepter/Blind Obedience. Slumber is low CMC and that Scry isn’t irrelevant early on, either.

Very meh. 10 snow permanents is a lot. Plus, even with a 20/20, it's 6 turns to attack the table to death... by then you could probably have sceptered everyone to death.

Sort of related, but the full-art game day promo Lavinias are CHEAP and look awesome.