Clash

Clash is an keyword action. It first appeared in Lorwyn and was reused in Morningtide. A design review in 2010 by Rosewater considered it a design failure.

Rulings

 * Each Lorwyn card that has clash says to "clash with an opponent." To do this, the following things happen in sequence:
 * 1) The controller of the spell or ability chooses an opponent. (This doesn't target the opponent.)
 * 2) Each player involved in the clash reveals the top card of their library.
 * 3) The converted mana costs of the revealed cards are noted.
 * 4) In turn order, each player involved in the clash chooses to put their revealed card on either the top or bottom of their library. (Note that the player whose turn it is does this first, not necessarily the controller of the clash spell or ability.) When the second player makes this decision, they will know what the first player chose. Then all cards are moved at the same time.
 * 5) The clash is over. If one player in the clash revealed a card with a higher converted mana cost than all other cards revealed in the clash, that player wins the clash.
 * 6) If any abilities trigger when a player clashes, they trigger and wait to be put on the stack.
 * 7) The clash spell or ability finishes resolving. That usually involves a bonus gained by the controller of the clash spell or ability if they won the clash.
 * 8) Abilities that triggered during the clash are put on the stack.


 * There are no draws or losses in a clash. Either you win it or you don't.


 * Each spell or ability with clash says what happens if you (the controller of that spell or ability) win the clash. Typically, if you don't win the clash, nothing happens. (Captivating Glance is the exception to this.)


 * If no one reveals a card with a higher converted mana cost (for example, each player reveals a card with converted mana cost 2), no one wins the clash.


 * An X in a revealed card's mana cost is treated as 0.


 * A card without a mana cost (such as a land) has a converted mana cost of 0.


 * Two cards (Entangling Trap and Rebellion of the Flamekin) have abilities that trigger whenever you clash. These abilities will trigger whenever you're involved in a clash, not just whenever you cause a clash to happen. It doesn't matter whether you win the clash.


 * One card (Sylvan Echoes) has an ability that triggers whenever you clash and win. This works the same as the two cards above, except it does matter whether you win the clash. Note that you can win a clash caused by a spell or ability your opponent controls.

Trivia

 * Clash was featured as rules card 4 of 5 in the Lorwyn set and 4 of 5 in the Morningtide set.