The official banlist for EDH can be found here (http://mtgcommander.net/rules.php). While individual playgroups can certainly adhere to their own banlists, most players follow the official banlist and refer to it to settle disputes. EDH is a casual format, so I understand why doing maintenance on its banlist is not as high a priority as the maintenance of Modern or Legacy’s banlists. However, if there’s to be an official banlist at all, it ought to be reasonable and consistent.
I don’t have that many problems with the list of cards that are banned. Sylvan Primordial, added later than most of the others on the list, sticks out. Why does a 7 mana green creature that doesn’t guarantee victory deserve to be banned? It’s effect is similar to that of Sundering Titan which is also on the banlist. Unlike Sylvan Primordial, I think Sundering Titan deserves its ban. Firstly, Sundering Titan is colorless, so it would be a staple for a larger percentage of decks. Secondly, Sundering Titan’s effect is much more powerful. While Sylvan Primordial can arguably get more value at times, you are required to destroy something from each opponent. This will clearly prompt the table to politically coordinate to keep you in check. On the other hand, Sundering Titan can potentially damage just one or two opponents. If that’s the case, the unaffected opponents may not feel the need to act, and the ones that are hit may be too weak to fight back.
I’ve been on the fence with Primeval Titan for a while now. I had always thought the reasoning of “it’s too powerful if it’s recurred” was faulty. The enablers for such recursion, such as Deadeye Navigator in particular, are not banned, and they have plenty of other targets to juice value out of. I maintain that the enablers are more abusive and should be banned first, but I do believe that it’s right for Primeval Titan to remain banned. The reason is that it’s powerful enough on its own. If it purely accelerated mana, it would be fair, but it can pull out all sorts of nonbasic lands like Dark Depths and Thespian’s Stage, Maze of Ith, or maybe even The Tabernacle at Pendrell Vale.
There’s a small group of cards that exploit Commander-specific rules. One of the best examples is Serra Ascendant. If you have 30 or more life – which you should because you start with 40 rather than 20 – it’s a 6/6 flying lifelinker for 1 mana. The lifelink on it makes it more difficult for your opponents to knock you below 30. It is banned in Duel Commander (http://www.duelcommander.com/banlist/). I’m not sure how this never got banned in EDH, but when it was printed in M11, they definitely weren’t thinking about how this would impact EDH. Blood Baron of Vizkopa, printed later in Dragon’s Maze, also gets stronger when you have 30 or more life, but it also requires your opponents to have 10 or less life, meaning it isn’t automatically active in EDH. Another card in this vein is Divinity of Pride. While this card is an 8/8 flying lifelinker for 5 mana as long as you have 25 or more life, I think this card is perfectly fair. Its mana cost of 5 black or white can be somewhat restrictive. Mainly, it’s just a big creature at 5 mana, and that’s fair.
There are a number of cards that are too powerful, in my opinion, for group politics to regulate. Sol Ring is the best example. It’s in every deck. It is the EDH staple. A lot of times, people won’t gang up on the guy with the early Sol Ring because either it’s too early in the game and they can’t do anything about it, or they figure it’s fair game. After all, it is unbanned, and everyone does have one. However, most of the time, only a fraction of the players in a given EDH game will draw Sol Ring in that game. Sol Ring is fair when everyone has it, or when no one does. Realistically though, I know Sol Ring will never be banned because it’s in every pre-constructed deck. It is a fun card for you if you draw it, but it doesn’t make the format healthier.
Take a look at the EDH and Duel Commander banlists side by side, and I’m sure you’ll spot a number of incredibly powerful cards that are legal in one and not the other. Though they are distinct formats, one multiplayer and the other 1v1, my main point, that the EDH banlist feels half-finished, still stands. I think EDH could be a healthy format as either a sort of singleton Vintage, or as format more like Duel Commander where many of the extremely powerful cards are banned. There needs to be a clear decision to go one way or the other, whichever direction it is. As it stands, the EDH banlist is a strange mix of both.