I've often heard it said that the Urza Block (Urza's Saga, Urza's Journey, Urza's Destiny) was the most powerful, broken block in Magic history, with decks able to win on turn 1 or 2. I also saw it stated (in some MaRo article) that something like 20 cards were eventually banned from that standard format in an attempt to restore balance. However, I've never seen a good, detailed explanation of what, exactly, went wrong, which cards were to blame, and how the uber-powerful decks of that era actually worked. Can anybody here offer an explanation or a link to an external source?
Preface: I've been drafting this for a few days now. I focused on the cards that were banned, because those were the most broken. I'm sure there were dozens of other combos not included here, and this is by no means giving the fullest extent of how the cards could be used to maximize their broken-ness.
The first step is to take a look at what cards were available at the time. Mirage had just rotated out, which leaves us with the Tempest block and of course Urza's block. This leaves us with some very powerful 0 and 1 mana artifacts: Lotus Petal, Mox Diamond, Ornithopter, and to a lesser extent, Spellbook.
Note that with Lotus Petal and Mox Diamond, you have yourself 2 mana available on your first turn without playing a land. (To be fair, both of those are part of Mirage, not Urza's.)Those mana can go into a Grim Monolith, which in turn gives you 3 mana when tapped. Make your land drop a Tolarian Academy and suddenly you have 6 mana available on your first turn, and you only needed four cards to do it. I think we can agree that 6 mana on the first turn is broken in an innumerable number of ways. This led the Academy to be the first to be banned.
Along with the Academy was Windfall. This was broken for a couple of reasons. First, consider a card like Divination, which has a card advantage of 1 for 3 mana at sorcery speed. (You draw two cards, but you had to spend 1 card to do it). When you also consider Azure Mage it becomes clear that in blue, 3 or 4 mana is appropriate for 1 in-hand card advantage. Now, consider how fast you blow through cards here: you dropped four cards (lotus, mox, grim, and academy) as well as any other 0 drop artifacts, and use a Windfall. You discard your 0 or 1 non-playable cards and pick up 7 more. Your opponent dumps all 7 of his and draws 7 more. You just gained 6 or 7 card advantage for 3 mana. That just isn't competitive.
The other aspect of Windfall is that your opponent is also playing combo. It was not uncommon for people to mull down to 4 to get their combo. While this will lower the card advantage you get from Windfall, it essentially wastes your opponent's mull! He now has to settle for whatever 4 or 5 crap cards are on the top of his deck. If you went first, then your opponent has not had an opportunity to play, but now is facing you with at least 6 cards on the battlefield, the ability to generate 6 or more mana a turn, and to top it all off, you just gave him a complete crap hand instead of the one he mulled to get. Bummer. So understandably, those were the first two to get banned.
In the next round of bans, you see Dream Halls get the axe. Now, without Academy and Windfall to pump up your early mana, this isn't as effective. It was costed such that you can't use it until turn 5, and you have to use two cards to do it instead of one. So since they were expecting you'd use this on turn 4 or 5, it would end up being very damaging. And under normal circumstances, it is. But there's one small problem. You discard that other card instead of paying the cost. This is supposed to make it so you can't use it. But Yawgmoth's Will made it so you could use it. If you Dream Halled two cards, you could cast the other two cards with Yawgmoth's Will. And with all the mana you have and card draw available, it's reasonable to pull this off.
Another one that was banned was Earthcraft. This card used to look like this:
However, it was decided that splicing text onto cards was a bad thing. So it was changed to
in the name of being easier to work with. Unfortunately, it had the side effect of making creatures with summoning sickness able to tap for mana, which is decidedly overpowered.
Fluctuator was banned because there's about 40ish legal cards with cycling, and they're all (Cycling 2). So they all basically let you loot them for free to burn through your deck. Cycling for free is broken. This combo didn't take much to come together.
Lotus Petal was banned for the combo listed out above, and I'm sure there were dozens of variants of it.
Recurring Nightmare was banned because three mana and a creature (probably 0 mana) was too little to return a creature from the graveyard to the battlefield, considering it goes back to your hand, not the graveyard (even if Yawgmoth's Will is active). It's even worse when the cards coming back are Great Whale, which yields infinite mana (although the infinite mana combo requires four lands on the board, and most games didn't last even that long!)
Time Spiral was the last of the second round to be banned from standard. It had the same problem windfall did, where you got to draw seven cards (including spells you've already played! How convenient!) and get the massive card advantage. Now this is 6 mana, not 3, and we know there's a gigantic difference between 3 and 6 (way way way more than twice as much). But as we've established, you can get 6 mana on your first turn... And to top it all off, you get to untap 6 lands. Umm, yes that's just a little too powerful.
The next big card to get the axe is Mind over Matter. This is simple: you discard (which we've established there's already massive card advantage here, which lessens the penalty...) and you get to untap an artifact (with academy, mana, or the mana artifacts themselves), creature (with earthcraft, mana, or Birds of Paradise), or land (mana). So you get even bigger mana amounts.
Memory Jar was so broken it was the only card to get an emergency ban. Basically you get to draw and play with 7 cards. As we've established your hand empties faster than a AK with a 14 round clip, you're going to get most of those cards out the turn you play it. And since 5 mana isn't all that much to get on turn 1, you might end up with this on turn 1, which when combined with another draw combo will give you access to 20 or more cards on turn 1. Broken? Yep. Unlike windfall, this doesn't kopper your opponents starting hand, as he'll get it back at the end of the turn. But you'll have another 4 or 5 permanents on the board, so what's he really going to do to you at this point anyway?
Like I said, these probably have even better ways to get the most out of them. But hopefully this gives an idea of exactly how these things were broken, and why Wizards reacted the way they did with all the bans. For what it's worth, this is the first genuine test of Wizards reacting to the fan base, and I would go so far as to say their biggest mistake up until that point and even to this day (needless to say they learned many lessons from it!)
There have been several times in MtG history that the game was broken for a while. Black Summer, with the proliferation of Necropotence decks, Affinity decks that abused cheap artifacts and artifact lands, and Combo Winter that resulted in the largest number of bannings. Mark Rosewater discusses why cards get banned and restricted. While not all the cards are from Urza block, about half are, and Mark includes some interesting information about the prototype versions of some of the cards and why they are broken.
A timeline of DCI banning/restrictions is available if you just want to know the timing of the various bannings. This article has some nice background on Combo Winter, some examples of Pro Tour decks, and links to tournament reports of what decks were being played at the time. It has an interesting piece from Randy Buehler on why Memory Jar was emergency banned, the first and only card to be banned before its release. If memory serves, Wizards even offered replacement packs if you opened a Memory Jar, because it was unplayable.
I realize I'm a year and change too late, but for anyone who stumbles across this post, just run a few games with the following list and you'll get it:
3 Dream Halls
4 Mind Over Matter
4 Grim Monolith
3 Thran Dynamo
4 Voltaic Key
4 Lotus Petal
3 Mox Diamond
4 Tolarian Academy
4 Memory Jar
4 Time Spiral
4 Stroke of Genius
Your sideboard would essentially be:
X Phyrexian Colossus
X Phyrexian Processor
As alternate win conditions.
X Defense Grid
For the Stroke mirror and the counters of any Counter-Phoenix or Counter-Slivers or Counter-Troll or Counter-whatever.
For the Gaea's Cradle decks. Nobody else had a chance of racing you, so nobody else deserved sideboard slots.
As for the main deck, there were, of course, variations. Maindeck Masticores and shaving numbers on Thran Dynamo and the enchantments to include Evacuation or Counterspell was common, but generally a bad idea. With a deck like this, you should be all-in. I experimented with a list that played Skyshroud Forest for Crop Rotation. If you didn't find Mind Over Matter yet, you could sacrifice an Academy to go get another Academy. I was super pissed when they banned Memory Jar because I had just spent all my money on a pre-order playset at age 10 as soon as the card was spoiled in Scrye or The Duelist or whatever magazine. Then they proceeded to ban the whole deck and all the trading and buying I had done for the past year.
We are now playing magic cards. We typically envision the scenario to be involved with summoning some creatures to attack or defend, casting some spells to hinder our opponents, setting up enchantments to boost up our advantages. If our opponents don't do anything we play, a typical creature fast attack deck of all era probably wins on turn 4 or turn 5(if not, we need to redesign our deck). What if we are playing against someone that does nothing to what you play, and suddenly wins the game on turn 2 or turn 3 or even the first turn? The word "broken" is used to address such issues. A lot of people don't want to play against such type of decks, but Urza's Saga block supplies numerous amount of cards that can make decks of this type.
What are the ways to win a Magic game?
In 2, if someone plays a game with 60 cards initially, and if you can force him/her to draw more than 60 cards at any turn, you win the game. If you can do this on turn 1, you win on turn 1. The cards in Urza's Saga block create such chance to become more likely to happen. This concept is not seen in nowadays blocks because cards that can lead to this scenario will not be created, but if you play Vintage format, you will still see this.
Stoke of Genius forces anyone to be named to draw X cards. If you have 60 mana for X, your opponent loses the game instantly. Many decks in Vintage uses this method to win the game ----- generating a very large amount of mana in a single turn and then force the opponent draw to win.
Voltaic Key + Grim Monolith = 5 mana Voltaic Key + 2x Grim Monolith = 7 mana
Tolarian Academy gives you 1 blue mana for each artifact you control. Together with Voltaic Key and grim monolith, we can have a lot of mana.
Crop Rotation makes sure that even if you don't have any Tolarian Academy in your hand on turn 1, you can still scoop it up. If you have 4x Tolarian Academy and 4x Crop Rotation, the chance that you can get a Tolarian Academy on the first turn increases from 40% to 65%.
Windfall/Memory Jar lets you draw 7 cards. If you have less than 7 cards when you cast/activate, you gain cards.
Mind Over Matter + Tolarian Academy + many artifact in play + a lot of cards in your hand is a combo that can generate such a huge amount of mana. Since Mind Over Matter is 2UUUU and Tolarian Academy generates blue mana, it's not difficult to cast early in the game.
Yawgmoth's Will allows you to play with less cards need to be drawn.
Yawgmoth's Bargain does not give you disadvantage if you play it early in the game. A sudden draw of 10 cards makes combo decks work immediately.
Time Spiral almost work like giving you an extra turn because you get to untap 6 lands and refill your hand.
Tinker can be used to call up Memory Jar.
Frantic Search not only lets you have a chance to gain the card that you want, but also untaps lands. If one of the land is Tolarian Academy, you gain more mana on that turn.
All those mentioned cards can be merges into a single extended deck. Apart from Mind Over Matter, all mentioned cards so far belong to Urza's Saga block. That's how powerful this block is.
I didn't mention how Tempest block and 6th Edition can help this type of deck. Scroll Rack, Dream Halls, Enlightened Tutor, Mystical Tutor, Vampiric Tutor can speed up drawing. Mana Vault is even cheaper than Grim Monolith. City of Traitors and Ancient Tomb give you more mana early in the game. Lotus Petal and Mox Diamond not only provide mana themselves, but also boost up Tolarian Academy. Furthermore, they allow you to play non-blue spells such as Yawgmoth's Will and Yawgmoth's Bargain.
This type of deck is played like this: You play Tolarian Academy + many artifacts, then you draw and draw and draw to give yourself more cards and more artifacts with Mind Over Matter in play(with 2 stroke of genius). With almost your library becomes your hand, force you opponent to draw more cards than he/she has in their libraries for the win. With Vintage format, from the help of power nine and Wheel of Fortune, if there were no restrictions on power nine and Wheel of Fortune, this type of deck finishes the game on turn 1 with probability at least 80%. We rarely see a turn 3 or above finish. If you are playing against a deck of the same type, it's almost like whoever wins the flip whoever wins the magic card game. What is the need of playing magic card then? Where is players' interactions during the game? A lot of players would not play such a card game.
Tolarian Academy + Mind Over Matter is not the only way to generate a large amount of mana in a single turn. Grim Monolith + Power Artifact, Worldgorger Dragon, Fastbond + Zuran Orb + Crucible of Worlds, and more other strategies can achieve. All combo decks requires the components of combo to be met. Yet the cards in Urza's Saga block mentioned in this article can also be used in other combo decks to speed up drawing just like Ancestral Recall. Those cards appear in almost every Vintage deck. They have perpetual effect in Magic. If we have a new combo in the future, those cards will always be used. Because of such versatility and such a large number of cards in a single block. Urza's Sage is the most broken block throughout history.
I am certainly no guru, and I play MTG very casually compared to some. I think the reason the Urza block got mixed reactions was the introduction of some powerfully good cards, and the number of these cards, that these days (certainly in modern format that my group plays mostly) probably aren't that powerful at all! The game of MTG has changed over the years.
My group have fond memories of that block! Gaea's Cradle. Serra Avatar. Defence of the Heart. Congregate. Crazy days!