Text (PS+errata): Kicker {W}. ; Target player can't cast spells this turn. ; If ~this~ was kicked, creatures can't attack this turn. [Oracle 2009/10/11]
This spell does nothing to spells that have already been announced prior to it resolving or to creatures which are already attacking. [Planeshift FAQ 2001/01/26] In other words, this spell does not counter another spell and does not remove attacking creatures from an attack. [D'Angelo 2001/02/18]
The player may announce spells in response to this spell. This spell does not have any effect until it resolves. [D'Angelo 2001/03/12]
This spell does not affect the abilities of permanents. It only affects spells. [DeLaney 2001/02/12]
This spell makes it so the player cannot declare any creatures as attackers this turn. [Barclay 2001/04/05] The card's wording may be updated in the near future to make this clear. Other cards may receive a similar ruling. [D'Angelo 2001/04/16]