Magic the Gathering Dual Lands were introduced in Revised the sixth set and third core set. Printing of Revised began in early April 1994 and continued until April 1995, when 4th Edition was announced. It is estimated that about 500 million cards of the set were produced, which fully eliminated the distribution problems of earlier sets. The cards of Revised were still widely available even well into 1996. The cards of Revised all had white borders and...
no expansion symbol. However, the cards were far paler than their Unlimited counterparts, and the three-dimensional beveling of the cards was cropped out. This made the set seem by some to be unprofessional and "washed out". The beveling was returned in 4th Edition, and the colors were much more vibrant in that set. The large print run meant that Revised basic lands were so numerous and common that it was uncommon to find any other lands in decks until several years later.
The collation of the cards made it possible for a basic land card to appear in the common and uncommon slots of a pack. This was intentional; the land cards were printed on the common and uncommon print sheets. Basic lands would get their own full print sheets in 4th Edition, making Revised the last tournament-legal set until 8th Edition in which basic lands could be found in booster packs.
One card-printing error of note appeared on the card Serendib Efreet. This blue creature card was misprinted with a green border and a picture of another card, Ifh-Bíff Efreet. The name, mana cost and rules text were of Serendib Efreet, however. The Revised version is now the most common due to the limited print run of the original, intended versions.
At this stage of development, cards were swapped out to alleviate problems. In later sets, cards were swapped in and out to change the feeling of the game, but the cards removed for the Revised edition were all cut for one of three reasons:
Being too powerful. In particular, the Power Nine were removed, but also such cards as Invisibility, Forcefield, and Berserk.
Mystifiers. Cards that were too confusing by the contemporary ruleset. Mystifiers included Raging River, Word of Command, Camouflage, Blaze of Glory, and Twiddle. Note that the effects of many of these cards were used in later sets, and several of the cards were even reprinted later in their entirety.
Too weak. Some very few cards were dropped for being too weak, in particular Copper Tablet, Ironclaw Orcs, and Dwarven Demolition Team.
Interestingly enough, many of the cards removed from the base set for the Fourth Edition were removed for same reasons as many cards were cut from Unlimited (although some were brought back in later sets). Such cards included Clone, Vesuvan Doppelganger, and Fork, cards which were either overpowered or offered strange rules interactions not suited for a base set.