MTG Salvation

Maherpotence
BBB
Enchantment
Skip your draw step.
Whenever you would discard a card, exile that card instead.
T: exile the top X cards of your library face-down. At the beginning of your next end step, reveal those cards and put them into your hand. You lose life equal to their total converted mana cost.

Needs better templating, and it's quite powerful, but BBB is pretty strict even for modern, and there's a HUGE risk of just killing yourself with it. Also, it would be obscenely fun to play with.

Total reversal
W
Instant
Whenever a player would lose lose life this turn, that player gains that much life instead.
Whenever a player would gain life this turn, that player loses that much life instead.

If there were a way to make this work, it would be amazing and really interesting as a card. A solid anti-aggro card that can buy time vs. Twin and Melira Pod, royally own Martyr, combo with Beacon of Immortality, but also is just using a card to gain some life and prevent some damage... I suppose it MIGHT be too good in Standard.

I'm just going to point out that cards being banned because they are unfun has happened before, will happen again, and is perfectly fine. However, it's probably never going to happen in Modern, because that rationale is reserved for old cards that are just plain dismal.
The most obvious example is the banning of Trinisphere in vintage, which was mainly banned for causing unfun games where no one could actually do anything. It wasn't dominant (certainly less dominant than other vintage decks that haven't gotten bannings), it wasn't any faster than the rest of the format, it was just blatantly unfun, and pushed people out of the format. It's perfectly fair for Wizards to say "this deck is absolutely unfun, it makes people not want to play the format, we're going to ban a card from it". Realistically, however, the threshold for that is so high it's never going to happen. We don't have decks like that in modern. Hopefully we never will. If we do, something has gone very wrong.
Here's a more relevant example for what that sort of deck might look like: Because of some new printings, a U/R land destruction deck emerges that can start destroying your lands on turn 1 and just keep doing that every turn. It uses Howling Mine to draw into more land destruction, while you can't cast the spells you draw. It doesn't play any win condition, just land destruction, some burn, and howling mine effects. It kills you by drawing you to death with Howling Mine. It never wins, and only rarely makes top 8, it doesn't violate the turn 3 rule. But it's strong enough that a lot of people play it, enough people that, if you're playing a ptq, chances are you'll run into it once and spend 2-3 games pulling out your hair and not knowing what to do. Wizards would probably ban a critical card or two from that to keep people from having to deal with it. I'd argue they would be totally justified with that ban, because decks that are sufficiently un-fun can do very real damage to the format.
Of course, that's probably never going to happen, because for all the faults in the New World Order and the direction wizards has been taking for the last several years, they're probably never going to print cards that make decks like that even remotely possible. And I'm sure we can all agree that, whatever you may say about storm, it is not that bad.

As for banning/unbanning right now: while I agree that it's WAY too early to seriously discuss, it's worth talking about any cards that could be safely unbanned. Golgari Grave-Troll, for instance.

I agree, that deck sounds sweet.
I built a tron deck that won by recurring Mindslaver with repeated Trash for Treasures. Things got out of hand fast.

I'm starting testing with a URw build running Rites/Griselbrand. The ability to go for Griselbrand was a HUGE coup in the summer of 2012 before Deathrite got printed, so it's a reasonable place to start for me. I'm putting Hivatron aside for now: it mainly flourished in a field of midrange decks, and with Jund gone, a lot of its natural prey has vanished.

Treasure Hunt/Seismic Assault?

On Chrome Mox: Chrome Mox was principally used in U/x and monoblue control decks, to keep up with combo and to be able to accelerate into their card advantage engines (using it to accelerate out a turn-1 Bob, for instance, was an excellent play, as was Counterbalance with the expectation of a Top next turn with countermagic backup). However, the same decks also used Thirst for Knowledge to draw into more threats and bin excess cards. This leads me to think that Chrome Mox would rather enable a new crop of control decks, in a similar vein to the Previous-level blue that existed after the Top ban, or even a fae control deck. In short: it'd be a strong addition, but it would be one that would bring in new decks, not boost old ones too much.

I've only ever played against Kiki-Pod, so maybe this is an incredibly stupid question, but how much does adding white actually give you? You get some solid hate cards that all seem fairly replaceable, maybe you can cast Finks more often, and Resto, but every time I play Kiki-Pod they always wind up with some card or another stuck in hand and taking a pile of damage from lands. Has anyone tried a straight RUG build with more Exarch-type cards could be a lot more consistent and allow for more basics.

Definitely look into standard. I would start by checking out their monoblack devotion deck, which frequently splashes green, and the green ramp decks. You should be able to find a decent home for her there. Vraska's actually a pretty decent card in standard, because she has a lot of utility against control decks (play her, destroy their Detention Sphere, and now they have to deal with Vraska and whatever card they had Detention Sphered in the first place). In Modern, though, you aren't going to get very far paying 5 mana for a card that destroys something and dies.

The Demon deck is good. But good isn't enough to consistently get a top 4. Twin might, with good play, but even then it depends on how competitive your meta is.

If you want to stick with Griselbrand deck, or either of those twin lists, post on the relevant boards. You'll get much better feedback, since only the players who are interested in that deck are posting. With their help, some tuning, and some practice, you can probably start posting pretty good records with any of those lists. If you don't really care what you're playing, though, you just want to succeed, go to the "What Deck should I play?" thread, post your preferred colors and/or strategies (for instance, "I prefer to play something in blue, red, or green, and I'm looking for a slower, controlling deck"), and some of the veterans/best players on this board will point you to a deck you'll like.

Check the Goryo's Vengeance thread in Established. If you want to place in the top 4 every week, though, you're gonna need something way more consistent. Twin, maybe. You can find it in Proven.

I think chrome mox could definitely be unbanned, but I doubt it will happen.
The problem with chrome mox is that it takes a card that you can't get back, which is a very real problem. In the past, control decks playing it circumvented that by playing raw draw spells from Bob to Gifts to Ancestral Vision, letting you dig your way out. Additionally, Chrome Mox gave you a way to use bad topdecks (like Ancestral Vision), and Thirst for Knowledge gave you a way to recycle topdecked moxen (because let's face it, a topdecked Chrome Mox is about as bad as you can get). In this format, however, there aren't enough good artifacts to justify thirst, especially with no artifact lands to splash, and the card advantage engine in the format revolves around casting a LOT of spells. Rather than using dedicated draw, control decks are largely relying on trading 1 for 1, playing a cantrip answer or two, and then rebuying them with Snapcaster Mage to pull ahead. That makes it a lot harder to sacrifice a card to Chrome Mox, since that's a card you won't be able to rebuy, and you need a critical mass of castable spells early in order to get ahead. It's possible Chrome Mox would enable different control decks (perhaps running the next-level blue style Thirst/Shackles/Trinket Mage/Academy Ruins plan), but I can't imagine it being all that good in a lot of decks. Maybe it'd be good in pod as a way to bin random bullet creatures you drew...

I think Golgari Grave-Troll is by far the easiest and most likely unban for the format. The only deck I can think of that it would see play in is Dredgevine, which REALLY isn't much of a threat in the format, and maybe some new brew, which would be a GOOD thing (a new brew enabled by Grave-Troll would almost certainly not be broken, so all it would do is improve format diversity). Honestly, I think it was an easier unban than either Bitterblossom or Wild Nacatl, at least without Dread Return.
After that, I'd hope Ancestral Vision would be unbanned, but I don't have a whole lot of hope. Seething Song would be nice, to be honest, though I can't blame Wizards if they're still too scared of storm. Honestly, at least for the moment, I'm happy with where the banned list is right now. It could use a few more unbannings, but the new format seems to have made blue control more viable (a major plus in my book) while not making it dominant (also a plus), it's weakened jund but not killed it, combo is back in force without feeling oppressive, and aggro is back without being in blue (Merfolk) or feeling more like combo than aggro (Affinity). While there are definitely cards that deserve an unban, I'd be cautious about disrupting the current balance.

Ritual Gifts put up a number of results (all in: 1 GP top 8, 1 GP top 16, control: too many to count on local scene and a couple solid records at PTQs). Hive Mind made some ptq top 8s I believe. I can't speak to AIR and Dragonstorm, however. And at the risk of getting off-topic, even if a ban only kills decks that aren't putting up any results, it still hurts the people playing them, which represents a very real harm to the overall diversity of the format, which has to be outwieghed by the benefits of the ban.

Also, a brief aside: In the Alara/Zendikar season, in between Worldwake and Rise, UW control managed precisely 0 top 8s until the very last week of the season (where it won 3 major tournaments in a row, in the last week before Rise came out). However, a rigorous statistical analysis of online win rates by archetype on TCGPlayer (see William Spaniel's Power Rankings articles at the time) found that UW Control managed a win percentage of over 70% at first, eventually falling to 59% at the end of the season. This made it by far the best deck by win percentage in the format (Jund hovered around 53% the entire time). The only decks even close to it at any point were Naya and White Weenie, neither of which ever managed to pass it. It was demonstrably the best deck in the format, by the only metric that matters: match wins. Why is that relevant? Because it shows that putting up results, especially if you only count top 8s or god forbid only count wins at GPs, pro tours, and even if you include SCG Opens (not relevant here) and PTQs, is a TERRIBLE way to determine if a deck is good. The sample size is minuscule, the amount of randomness involved is immense, and it's strongly influenced by the choices the pros make, since their playskill and team testing gives them a better chance of a top 8 even if they choose a weaker deck. Statistical analysis of match win rates, assuming a large enough randomized sample of games, is infinitely better. If there isn't a good enough sample available, you can divide top 8 presence by overall presence in the field, or day 2 presence by day 1 presence. That needs a decent sample as well, but a much smaller one, and it's still more accurate that just raw results.

I'm wondering about this since the heavy two first banning rounds.
There would be an even better format between modern and standard, in Make-your-own-Standard, where you pick two blocks and a coreset and build a deck with it. However it would require a few more cards banned probably.[/quote]

I have to agree with what other people have said, that this format, while awesome, would be a HUGE logistical headache and probably not worth it.
There are actually a lot of formats of that type. A while back, my team (which, if you haven't noticed, likes to take breaks in the standard season to try crazy new formats) decided to try out a format where all non-ante cards are legal and unbanned, but the total cost of your deck could only be $30 for the maindeck and $10 for the sideboard, with prices established by Starcity Games. It's a very fun format (also, surprisingly enough, significantly more powerful and broken than Modern is*), but it would be a NIGHTMARE to do deck checks at a sanctioned event.

*:

It's not an infinite loop, but if you're just interested in forcing a draw (without going to time), Biorhythm on an empty board simultaneously sets both players life totals to 0, forcing the draw.