Urza's block

Urza's block (also referred to as "Artifacts block", "Urza block", "Urza's Saga block", "Saga block") is the fourth block, consisting of the large expansion Urza's Saga and the two small expansions Urza's Legacy  and Urza's Destiny. Sets in the block were released in 1998 and 1999.

Mechanics
Keywords introduced in this block: Cycling, Echo.

Mechanics include growing enchantments, sleeping enchantments and the "free" mechanic.

History
Urza's block is considered the most powerful block ever printed as it had the most cards from a block (such as Tolarian Academy, Memory Jar) banned in tournaments.

The Urza's Saga design team originally conceived the block as an enchantment block, but in order to capitalize on the Urza story, the brand team dubbed the block The Artifact Cycle. That name was also used for a series of four books chronicling events related to the Antiquities expansion and Urza's block. In development R&D made a few mistakes which led to the set's high power level, labeled "bah-roken" by Mark Rosewater. Some of those broken cards were artifacts. "So the enchantment theme kind of got buried. In fact, very few players even recognized it as an enchantment block."

In fact, so many broken cards were in Urza's Saga that the following period became known as Combo Winter. Too many overpowered cards and combos filled the tournament. This moved the DCI to ban a large number of cards in December 1998, and the CEO of Wizards of the Coast to threaten to fire the R&D team if they broke the constructed environment again.

Pairs

 * Destroy: Based on Rain of Salt from Urza's Saga, Urza's Legacy continued with Peace and Quiet  / Rack and Ruin  pair.
 * Until end of turn: Based on Symbiosis from Urza's Saga, Urza's Legacy continued with Hope and Glory / Sick and Tired  pair.