Of the 143 cards in Nemesis none were a reprint of a previous card.

In Nemesis, new Rebels, Mercenaries, and Spellshapers were added to the Mercadian Masques repertoire. The Flowstone creatures, originally introduced in Stronghold had another showing. Other mechanics include:

• Fading — Normal permanents enter the battlefield and stay there until removed, cards with Fading only have a limited lifespan. Fading always appears on Magic cards as "Fading X". A card with Fading X stays on the battlefied for X full turns after the turn it entered the battlefield, and is afterwards put into the graveyard.

• Seals — This is a cycle (one card in each color) of enchantment cards that have no immediate effect on play when cast. They can be sacrificed for an effect, though.

• Free spells — Nemesis further explores the idea of spells that can cast for an alternate cost, not involving mana. This was first introduced in Alliances and was also a mechanic used in Mercadian Masques.

• Laccolith creatures — This is a kind of beast that can deal their combat damage immediately upon becoming blocked, meaning that these creatures can deal damage even before creatures with First Strike. The Laccolith only appear in red.

Several cards from Nemesis had a major impact on tournament play. Most of these were cards with the Fading ability.

• Lin Sivvi, Defiant Hero - Lin-Sivvi had a huge impact on tournament Magic. At the 2000 Pro Tour New York a Rebel deck, relying heavily on the strength of the card, was by most considered to be the dominant deck,and was indeed played by almost half the competitors. Eventually six of the eight final decks were Rebel decks, most of them indeed packing the allowed four defiant heroes. Lin Sivvi was banned from block-constructed play after that Pro Tour, but in the following season in the finals of the Standard Pro Tour held in Chicago both decks were Rebel decks with Lin Sivvi.

Story: The Phyrexian invasion of Dominaria is nearing; the Dark Lord's plans are almost complete. Only the Planeswalker Urza stands in his way. At the same time, Yawgmoth's Inner Circle decides on the election of the evincar to replace Volrath. The Phyrexian emissary Belbe has to choose between Greven Il-Vec, Ertai, Crovax, and the newly-returned Volrath.