Demise OTKs is using a Advanced Ritual Art or another ritual spell card to send monsters to the graveyard, activate Demise's effect, and summon another card which can use the cards sent to the graveyard to summon another monster which has at least 5600 ATK or has a effect that can reduce the opponent's life point to 0.
One version of Demise OTK uses the following cards:
- Demise, King of Armageddon
- Advanced Ritual Art
- Two Insect Knights and/or two Neo Bugs in your deck
- Doom Dozer and/or Metal Armored Bug (or any normal monster with 2800 or more ATK).
- Great Maju Garzett, Megamorph and/or Metamorphosis(the last one only in the Traditional Format).
First, use Advanced Ritual Art, sending two Insect Knights or Neo Bugs in your Deck to your Graveyard to Ritual Summon Demise, King of Armageddon. Then, pay 2000 Life Points to use Demise, King of Armageddon's effect to clear the whole field. Next, Special Summon Doom Dozer by removing from play the two Insect Knights or Neo Bugs in your Graveyard. Next, either summon Great Maju Garzett or play Megamorph on Doom Dozer (you probably will have less Life Points than your opponent), or play Metamorphosis on Doom Dozer to Fusion Summon Cyber Twin Dragon (in the Traditional Format. Attack, and you win the Duel.
The combo has been weakened with the Limiting of Advanced Ritual Art in the March 2008 Lists.However, Manju of the Ten Thousand Hands, Senju of the Thousand Hands and Sonic Bird may help to find the key cards for the combo. Trade-In and Common Charity are also good support-cards.
Commonly used support-cards are Monster Reborn and Swing of Memories (also Premature Burial in Traditional) to bring back Metal Armored Bug and the other Insect monsters.
A particular variation to the deck involves also Sky Scourge Norleras and many Fairy and Fiend monsters (such as Dunames Dark Witch and Archfiend Soldier) which are put in the Graveyard by the effect of Advanced Ritual Art in order to summon Norleras. However, this variation works best in the Traditional Format because of the possibilities given by Dimension Fusion, Chaos Emperor Dragon - Envoy of the End and Black Luster Soldier - Envoy of the Beginning. The deck also uses one copy of Blue-Eyes White Dragon.
Yet another variation involves Geartown, Ancient Gear Gadjiltron Dragon, and Blue-Eyes White Dragon, as well as the draw card Trade-In. Use Trade-In or Montage Dragon to dump Blue-Eyes White Dragon into the graveyard (Foolish Burial also works, but is not necessary to keep the speed of the deck. Play Geartown, and then use Advanced Ritual Art or End of the World (easily searched by Sonic Bird, Senju of the Thousand Hands, or Manju of the Ten Thousand Hands) to ritual summon Demise, King of Armageddon. Clear the field using his effect, and special summon an Ancient Gear Gadjiltron Dragon due to Geartown's effect. Use Swing of Memories to summon a Blue Eyes or two, then use support cards like Megamorph or even Limiter Removal for the OTK. This also can be supported with Great Maju Garzett. It is also wise to keep a Gorz the Emissary of Darkness in this deck in the rare case that you have nothing to play. You might also think about using Dark Coffin or Statue of the Wicked. If these cards are set when Demise, King of Armageddon uses it's effect, then you'll get an instant advantage over the opponent.
Another variation, similar to the one above, involves Geartown, Ancient Gear Gadjiltron Dragon, and Evil Hero Dark Gaia. First, play Geartown. Next, use Advanced Ritual Art to Ritual Summon Demise, sending one Archfiend Soldier and one Beta The Magnet Warrior. Use Demise, King of Armageddon's ability to clear the field and summon an Ancient Gear Gadjiltron Dragon when you destroy Geartown. Finally, use Dark Calling, and remove from play the Archfiend Soldier and Beta The Magnet Warrior to create a Dark Gaia with an attack of 3600. The total damage these three monsters will do when they attack directly is 9000, enough for an OTK. This variant can make good use of the Spell card Trade-In to send extra copies of Demise or Gajiltron Dragon to the Graveyard to draw extra cards. One or two copies of Valkyrion the Magna Warrior is also recommended for use with Trade-In, and because it has one of the highest attack scores of any Rock-type monster, giving you the potential to create a powerful Dark Gaia and OTK even without the Ancient Gear Gajiltron Dragon or Geartown.
Another variation of this OTK uses Dark Strike Fighter to win. This OTK uses Demise, King of Armageddon, "Black Salvo", Advanced Ritual Art/ Contract with the Abyss, and 2 monsters with at least 1 DARK Machine. Using Advanced Ritual Art to send 2 level 4 DARK Machine-type monsters(usually Mechanicalchaser or Blocker) to the graveyard and summon Demise, King of Armageddon. Then pay 2000 Life Points to destroy all cards on the field. Then summon "Black Salvo" and special summon one of the monsters you sent to the graveyard using ARA (Advanced Ritual Art) to synchro summon Dark Strike Fighter. Then attack your opponent directly with both monsters. Then, tribute Demise, King of Armageddon with Dark Strike Fighter's effect to inflict damage then tribute Dark Strike Fighter for it's own effect for a total of 8000 damage. If you had Contract with the Abyss in your hand, the OTK is more situational since it requires 2 Level 4 monsters with at least 1 DARK Machine. This combo, however, is now resticted to Traditional Format, now that Dark Strike Fighter is Forbidden.
Because Demise itself is now Limited, due in part to several other poential new combinations that would make it deadly, the Demise OTK is even harder to do, and seems unlikely to become popular again.