The Madness mechanic in Magic: the Gathering, although introduced in a limited amount in only one expansion set, has had great impacts on the way several formats (playing environments) work.

Only 10 cards with the madness mechanic were introduced, each color receiving 2 cards with the ability.

The cards are:


Green
  • Basking Rootwalla
  • Arrogant Wurm

  • Blue
  • Circular Logic
  • Obsessive Search

  • Red
  • Violent Eruption
  • Fiery Temper

  • Black
  • Psychotic Haze
  • Strength of Lunacy

  • White
  • Frantic Purification
  • Strength of Isolation

  • I have only included a summary of Green's madness cards because one non-Green card has seen any significant play.

    Green

    Green recieved two Madness creatures for it's share of the cards. They are the only Madness creatures in the game, save a variant from Apocalypse and Mirage that depended on your opponent forcing you to discard them. The creature Basking Rootwalla also happens to be the only 0 mana Madness spell in the game. Both creatures (in theme of the madness cards) have Madness costs lower than their casting costs, enabling fast plays of the creatures, sometimes netting you card advantage (based on the method of discard).

    Most likely the best madness cards, Green's madness cards no doubt changed tournaments in all formats except Type 1, although a "budget madness" became possible.
    Extended:

    After the rotation, there was a general weakining of the playing field for control decks and combo decks. With Force of Will and Swords to Plowshares out of the enviornment, Control decks will be scrambling to compensate for their lack of key cards, and Combo decks will lose precious life and time making up for the lack of duel lands, and their ability to abuse "fetch lands" (Mirage lands that came into play tapped and found a land card of one of two types, such as "Mountain Valley or "Bad River") and Land Grant will hurt their mana base and slow them down. This lack of control may provide an enviornment in which decks abusing the madness creatures can thrive.

    Without Survival of the Fittest, the Madness green cards will not be as broken as they can be in Type 1.5, but still, powerhouses like Wild Mongrel exist in Extended. Cards like Pack Hunt exist in the format, and playing any deck using Gerrard's Verdict will be much weaker than normal. Counter decks will need to rely more on Powder Keg as a method of eliminating them. Oath decks should still be able to handle the swarm of efficient creatures, although it may be forced to run cards like Crater Helion more often. Reanimator style decks can still function due to the influx of cards like Entomb.

    Update:
    UG Madness has become a fundamental part of Extended. The ability to abuse Intuition, and the best creatures in the format has allowed for UG to rise to be a tier one deck. It's rise to power was a result of the superior discard mechanism in the form of Waterfront Bouncer (synergestic with the crucial creature, Gilded Drake, an answer to Reanimator). Madness could off an active Oath and other creature strategies. Of course, the deck rolled over to the now banned beast, Tinker. After the ban hammer struck extended and killed of the abusive combo decks (Hermit, Gobvantage, The Clock, Twiddle Desire, and Tinker) UG Madness became a major contender to the "big three" (RDW, Tog, Rock). The next season will show if Madness has enough punch to it to continue to compete when Affinity is legal.



    Type 1.5

    Type 1.5 has been changed less than Extended by the introduction of Madness creatures, but still a great deal. The once almighty Hymn to Tourach faces the threat of free creatures falling onto the table. B / W control decks will be hit the most, with their valuable discard such as Gerrard's Verdict becoming their own enemy. Combo decks that run cards such as Anvil of Bogardan are pointless now, with the threat of free creatures breaking the lock. An active Mongrel now offers the threat of letting loose 3 creatures in succesion on turn 3...during the Counter Player's discard step (because it's instant speed). The fact that the counter player can't handle all the threats anyway during the end of his turn is practically irrelevant when one considers that the counter-player tapped out during his own end step.

    Most importantly, are the implications of Madness with the Exodus rare, Survival of the Fittest. Survival allows the player to discard a creature card to search his library for a creature card and put it into his or her hand. The activation of this ability is simply G (one green mana). Survivaling a Basking Rootwalla for a Basking Rootwalla is possible, and disgustingly efficient. At the loss of no card advantage, four creatures with an ability can be brought into play at instant speed. After the Rootwallas are brought in play, the caster can search for Wurms and play them as well. A single Survival will spell doom for any counter deck, regardless of it's tricks with Squee and Recur.



    Type 2:
    Note: This is during Odyssey / Invasion, and Odyessey / Onslaught Type 2 only. After the rotation of the Odyssey block, Type 2 lost all madness cards.

    This format has had the greatest repercussion from Madness. The Rootwalla has brought about several deck archetypes - Blue / Green Madness being the most prominent one. This deck revolves around using the 2 Madness creatures and the Madness counter spell to bring about a speedy victory (turns 4-5), with the control of the color Blue (Circular Logic, Upheaval). Many cards that were seeing a fair ammount of tournament play are being kept in the sideboard for fear of this deck.
    Some example cards are:

  • Recoil
  • Probe
  • Gerrard's Verdict
  • Type 1

    Madness is Type 1 must compete with Hulk, TnT, Fish, MindSlaver, World Gorger Dragon, Draw7, Keeper, Rector-Trix, The Clock, Raffinity, Stax, Stompy, and fellow budget decks. Type 1 only has three interesting abusers for the madness mechanic that the Madness player doesn't have access to in most formats. They are the cards Lion's Eye Diamond, Bazaar of Bagdhad, Survival of the Fittest.

    Lion's Eye Diamond has been banned to reduce Long's power (although DeathLong is being experimented with), leaving Madness with only two other potentially broken abusers. Bazaar is insane, but the power that Bazaar wields in Madness pales before that WGD can offer.

    Survival of the Fittest in Madness is slow enough that the deck should just run Welder and a fatty with it's going to run Survival, and any deck with Survival and Welder is better off being played like TnT (with Workshops of course).

    After considering that there is no LED to abuse, that the average combo deck can win before turn 4 (Madness can rarely win before turn 4), that TnT is a superior aggro deck, and that the control decks are absolutely insane, there is little reason to play Madness. However, if you own Tropical Islands, building a Madness deck is a lot cheaper than something like Stax or Dragon, or even Fish. Don't consider this deck if you want to Top 8.