A spell or ability that requires targets may allow zero targets to be chosen. Such a spell or ability is still said to require targets, but that spell or ability is targeted only if one or more targets have been chosen for it.
July 16, 2010 · Magic 2011
rule 115.6 not present in this release
June 18, 2010 · Archenemy
In a multiplayer game using the shared team turns option, teams rather than individual players have priority. See rule 805, "Shared Team Turns Option."
February 1, 2010 · Worldwake
In the Two-Headed Giant multiplayer variant, teams rather than individual players have priority. See rule 806, "Two-Headed Giant Variant."