Mercadian Masques consists of 350 cards: 110 each of commons, uncommons, and rares plus 20 basic lands. It was the first large expansion to use the new 6th Edition rules. This was the first set to have an accompanying fat pack. It reprinted a number of cards from previous sets, many of which have not been reprinted since.
Nemesis prerelease events were held on February 5, 2000. At these events the prerelease card, a foil Rathi Assassin, was handed out. The set was officially released on February 14, 2000. The 143 Nemesis cards come in three rarities, common, uncommon, and rare. 55 cards are common, 44 are uncommon, and 44 are rare. Nemesis booster packs include 15 cards, one rare, three uncommon, and eleven common. About every 100th card is a randomly inserted premium foil card.Nemesis had a fair share of cards appear in well-placing tournament decks. Many of the cards with Fading were quite powerful; the cards Parallax Wave, Parallax Tide, Blastoderm, Saproling Burst, and Tangle Wire all appeared in decks in various formats. Of the 143 in Nemesis none is a reprint. 22 cards from Nemesis have been reprinted afterwards, 16 in Core Sets.
The Prophecy expansion consists of 143 cards. When released, was one of the least popular sets ever among tournament players. Though many casual players liked it because of the enormous Avatar and Winds cycle, both of which had a big effect at a big cost, it had relatively little impact on Standard tournaments. Magic head designer Mark Rosewater has also voiced his opinion, that Prophecy is the second-worst designed Magic set of all time. (behind Homelands) As of February 2012 only 21 cards from the Prophecy expansion have been reprinted.
Unusually, Masques introduced no new keyword abilities to the game. However it was advertised as introducing new creature types, which were continued throughout the block: Two of these types were rebels and mercenaries, creatures able to search through their controller's library and "recruit" creatures of a specific type directly into play. Another type was spellshapers, creatures that had repeatable activated abilities that mimicked various classic spells, potentially turning otherwise useless cards into powerful effects. All of Masques's spellshapers required paying mana, tapping the creature and discarding a card to use their ability. Masques also reintroduced spells with alternative casting costs. This mechanic had not been used since Weatherlight.
In Nemesis, new Rebels, Mercenaries, and Spellshapers were added to the Mercadian Masques repertoire. The Flowstone creatures, originally introduced in Stronghold had another showing. Nemesis introduced the Fading mechanic, which had creatures enter the battlefield with X counters on it, but be placed into the graveyard after X turns. Nemesis has a cycle (one card in each color) of enchantment cards called seals that have no effect until sacrificed. It again experiments with spells with a non-mana costs.
The main theme and mechanic of Prophecy was lands; specifically, whether lands were untapped or not. Similarly, the Rhystic cards gave the player an advantage if no other players paid a certain amount of mana. Prophecy introduced no keyword mechanics.
For years after its release Mercadian Masques was considered to be an underpowered set. Reportedly, the designers were extremely gun-shy following the runaway power of the Urza's block which had led to many bannings. In response to the experience with the Urza's block the developers of Mercadian Masques dialed back the power of the set, resulting in a set that in its time was considered to be weak; the same phenomenon would take place between the latter-day Mirrodin block and Kamigawa blocks.
However, the set did produce a respectable amount tournament-quality cards. Gush was for some time restricted in Vintage and is still banned in Legacy. Food Chain combined with Goblin Recruiter from Visions to form a powerful combo deck that eventually led to Goblin Recruiter's banning from Legacy. In its time Rishadan Port was a dominant mana denial card in Standard, and is still used for this purpose in Legacy. Other cards that still have impact on Legacy include primarily cards that can be cast without paying their mana cost such as Land Grant, Misdirection, and Unmask.
Each of the Mercadian Masques theme decks has at least one spellshaper, a theme of the set. The pre-constructed theme decks are Deepwood Menace (green-red), Disrupter (black-red), Rebel's Call (white), and Tidal Mastery (blue-white).