(The following information is from this article detaliing the Banned/Restricted List Changes and this forum post on MTGCommander.net)
Today's another Banned/Restricted announcement, this time a normally scheduled one. All normaly Banned/Restricted updates happen on the 20th of ever 3rd month (so there are 4 regularly scheduled updates in a year). This is the first Banned/Restricted announcement since Jace, the Mind Sculptor got banned in Standard, Stoneforge got semi-banned in Standard, and the Modern official Banned list was released.
And today sees more changes than are normally seen out of a Banned/Restricted Update. Let me put it this way...the only formats NOT hit seemed to be Scars of Mirrodin block and Standard. Everything else that has sanctioned play at least once a year got a Banned/Restricted List update.
So let's go ahead and get started off with the first rotating format to get updates...EXTENDED!
Extended Ban List Update
Jace, the Mind Sculptor
REASON: Basically, every card banned here was a big player in too many successful decks over the last 3 years in Standard. Players seemed to complain about how the format was shaping up, so these new bans are a means to help revitalize interest in Extended.
NOTE: There is no partial banning of Stoneforge Mystic. She is completely banned in Extended.
Now let's move on to our most recent Eternal format, MODERN!
Modern Ban List Update
Green Sun's Zenith
Rite of Flame
Blazing Shoal delivered too consistent of a quick kill: Turn 1-2, throw out Blighted Agent or Inkmoth Nexus, Turn 2-3 cast Blazing Shoal and ditch a Dragonstorm/Reaper King/Progenitus to get lethal Infect damage.
Cloudpost was dominating, allowing very quick mana acceleration in combination with Vesuva and Glimmerpost. Supposedly, these decks could hit 15 mana by Turn 4. This was deemed unhealthy.
Green Sun's Zenith: Early or late game, it's just too efficient at what it does. It can either act as early mana acceleration by getting a Dryad Arbor or get a late-game beater like Primeval Titan. It was getting to a point where all Green decks were going the Green Sun's Zenith route and no other way.
Ponder and Preordain: Like Brainstorm and Ponder in Vintage, they're too good at what they do. In some combo decks, it became too easy to find combo pieces...just like Brainstorm.
Rite of Flame: Combo enabler that was seen way to often. One of the highest finishing decks at the latest Pro Tour won 9 out of 10 games with it and the games ended VERY quickly.
Next up, we're moving to the more restrictive format...LEGACY!
Legacy Ban List Update
REASON: Mental Misstep was a mistake...a BAD mistake. Printed to help non-blue decks have access to a Force of Will-type card, instead blue deck adopted Mental Misstep ALONGSIDE Force of Will. What happened to the Legacy metagame was exactly the opposite of what they intended. They planned to ban the card if the results were poor, and, well, they were.
So congratulations! Unless you're playing Standard, Scars of Mirrodin block constructed, or Vintage, you have no opportunity to play Mental Misstep.
And almost finally, we get some good news with an unrestriction in the most open format for legalities, VINTAGE!
Vintage Restricted List Update
NEWLY UNRESTRICTED (4-of):
Fact or Fiction
REASON: Fact or Fiction was powerful long ago, and the time seems to have come to unban it and see if it's as big a powerhouse now as it was then. This goes along with unbannings like Grim Monolith and Time Spiral in Legacy where each proved to be not overpowered in the present day.
ULTIMATELY LASTLY AND FINALLY...finally (:p)...we have a COMMANDER update with one unbanning and 1 banning as a Commander.
Commander Ban List Update
Lion's Eye Diamond
BANNED AS A COMMANDER (still okay in the other 99 cards of your deck):
Erayo, Soratami Ascendant
Lion's Eye Diamond: Sheldon Menery, basically the internet leader for EDH, and his rules committee feel that while Lion's Eye Diamond COULD have potential issues, the benefits of letting newer players explore "non-scummy" ways to use it seems to be worth unbanning. Or something like that? But they'll keep a close eye on it and see if it ends up hurting the format.
Shahrazad: Meant to let newer players have some fun with subgames, the rules committee was finding that people were building Shahrazad-based decks just to annoy players. That's never good for the game. Whatever exception allowed Shahrazad to be played was removed and it's not completely banned.
Erayo, Soratami Ascendant as a Commander: Simply put, he effectively ends games as soon as he hits the board. Sheldon and the rules committee don't like Commanders that do that. Players learn the hard way that, unless they have a very narrow set of answers, they can't deal with Erayo once it flips.
All of these changes except Commander take effect on October 1st, so enjoy your Ponders, Preordains, Mental Misstepts, and Rite of Flames a little while longer. For Commander, the changes are immediate, as best I can tell.
That is all for tonight. Comments? Suggestions? Feel free to post here. :)