From Archon Arcana - The KeyForge Wiki

Compatible Format(s): Archon, Sealed

Description: Each round of this tournament consists of best-of-three matches. For the first game of each match, players use their own decks. For the second game, each player swaps decks with his or her opponent and plays using his or her opponent’s deck.

If the third game occurs, players bid chains to use the deck which won both of the previous games. The player who brought the deck starts by bidding 0 chains, and then the players take turns outbidding each other until a player declines to bid higher. The player who bid the highest uses that deck for the third game (with their bid number of chains applied at the start).

Philosophy: Chains are a balancing mechanic built into the base rules of KeyForge. They can be utilized to allow two decks with a large difference in strength to play at roughly even footing. This helps to emphasize the skill of the player over the strength of an individual deck and allows each player the chance to do well with whatever deck they happen to use.