A.28.1- The ability is written "Madness
A.28.2- This ability has two abilities that are part of it. The first
one is "If a player would discard this card from his or her hand, that
player discards it but may remove it from the game instead of putting it
into his or her graveyard." The second one is, "Whenever this card is
removed from the game this way, until he or she passes next, he or she
may play it at any time he or she could play an instant as though it were
in his or her hand by paying
A.28.3- Playing a card using this ability follows the rules for alternate costs (see Rule E.1). [CompRules 2002/02/20 - 502.24b]
A.28.Ruling.1- The fine grain timing around this ability can be a bit difficult to follow. What happens is that if you discard the card (it does not matter why you are discarding), then you get the choice of whether or not you want a chance to play the card. If you don't want to, simply put it in your graveyard as normal. If you might want to, you do not pay at this time. Instead you remove the card from the game and put a triggered ability on the stack (as per those rules, see Rule A.3). What this means is that players may respond to this trigger with other spells and abilities. Once any responses are resolved and both players pass, the triggered ability resolves. You can now play that spell just like you would as if it were in your hand (but it is not in your hand) by paying the Madness cost instead of the mana cost. And this spell can be played any time an instant is legal, regardless of its type. As normal, you can only play a spell or ability when it is your opportunity to do so. The text saying "until he or she passes next" means that you can choose to put other spells or abilities on the stack prior to playing the Madness spell. [D'Angelo 2002/02/23]
A.28.Ruling.2- You are in no way required to play the spell even if you choose to remove it from the game. You can simply choose to pass when you have a chance to play something and the Madness spell is placed into the graveyard. The timing for putting it into the graveyard is also a bit odd since this is also a triggered ability. When you pass, put a triggered ability on the stack. When that ability resolves, the card is put into the graveyard. [D'Angelo 2002/02/23]
A.28.Ruling.3- Madness does not allow you to discard the card just because you want to. Another spell, ability, or game rule has to cause the card to be discarded. [D'Angelo 2002/02/23]