by Mark Rosewater
The second format of the Invitational is a brand-new format we call B.Y.O.B.-Build Your Own Block. This format requires players to build decks using only three expansions. The first expansion must be a large expansion: Ice Age, Mirage, Tempest, Urza's Saga, Mercadian Masques, or Invasion. The second must be a first small expansion to a large one: Homelands, Visions, Stronghold, Urza's Legacy, or Nemesis. The third must be a second expansion to a large one: Alliances, Weatherlight, Exodus, Urza's Destiny, or Prophecy.
This format is a variant of last year's Block Party, which required each player to bring a Constructed deck from any block. Although B.Y.O.B. allows more flexibility, it also has a much longer banned list-in B.Y.O.B., a card is banned if it's banned or restricted in any format.
Each year we include one new Constructed format to test the players' deckbuilding skills. Like Duplicate Limited, B.Y.O.B. forces the competitors to deduce a completely new metagame. Although several invitees may come to the event with preexisting (and pre-tested) block decks, expect to see some creative mixing and matching. If the players are ambitious, we may even see one or two new archetypes emerge.