"Three" is not a number.

Featured Duel: Seto Kaiba vs. Noah Kaiba - Part 2

Noah Kaiba's Turn

After revealing his Deck Master to be "Shinato's Ark", Noah activates its special Deck Master ability: adding all the monsters sent to the graveyard to itself.

Summons "Spear Dragon" (1900 ATK / 0 DEF) and attacks Noah directly.
Noah activates his Deck Master's ability, Special Summoning "Vampire Lord" (2000 ATK / 1500 DEF) on his side of the field in Defense Position to block the attack.
"Vampire Lord" is destroyed and returns into Noah's "Shinato's Ark". Thanks to "Spear Dragon's" special ability, it inflicts damage to Noah despite his Defense Position monster (Noah: 3200 → 2800 Life Points).
"Spear Dragon's" secondary effect switches it to Defense Position after an attack.

Activates "Pot of Greed".
Activates his Deck Master's special ability: "Kaiser Sea Horse" allows him to summon a Light monster with one less tribute. He chooses "Different Dimension Dragon" (1400 ATK / 1500 DEF) in Defense Position (NOTE: In the real game, "Different Dimension Dragon" has 1200 ATK).
Sets three cards.

Activates Spell Card "Deepest Impact", destroying all monsters on the field and halving both players' Life Points (Noah: 2800 → 1400 Life Points) (Seto: 1400 → 700 Life Points).
"Giant Rex" goes into Noah's "Shinato's Ark".
"Different Dimension Dragon" cannot be destroyed by the effects of Spell or Trap Cards that don't have a specific target, so it remains on the field.
Noah activates Spell Card "Ice Age Panic" to summon "Last Tusk Mammoth" (800 ATK / 1200 DEF), and uses it to attack "Different Dimension Dragon".
Seto activates Trap Card "Ring of Destruction" to destroy "Last Tusk Mammoth", then plays Spell Card "Ring of Defense" to prevent the damage of "Ring of Destruction" to himself. Life Points (Noah: 1400 → 600 Life Points) (NOTE: In the real game, "Ring of Defense" would have prevented the damage to *both* players).

Switches "Different Dimension Dragon" to Attack Position.
Discards "Thunder Dragon" from his hand, activating its effect and adding two "Thunder Dragons" from his Deck to his hand, which he then fuses with Magic Card "Polymerization" to form "Twin-Headed Thunder Dragon" (2800 ATK / 2100 DEF).
All three of Kaiba's "Thunder Dragons" go into Noah's "Shinato's Ark".
Activates Spell Card "Quick Attack", allowing "Twin-Headed Thunder Dragon" to attack this turn (NOTE: In real life this is not necessary, but this Duel follows the Battle City Rules).
Noah activates "Shinato's Ark", Special Summoning its stored monsters "Giant Soldier of Stone" (1300 ATK / 2000 DEF) and "Giant Rex" (2000 ATK / 1200 DEF), both in Defense Position.
Seto activates Continuous Trap Card "Dragon's Rage", which allows his Dragon-Type monsters to inflict damage to Noah's Life Points, provided their ATK is higher that the defending monster's DEF.
Attacks "Giant Rex" with "Different Dimension Dragon" (Noah: 600 → 400 Life Points).
Attacks "Giant Soldier of Stone" with "Twin-Headed Thunder Dragon", intending to defeat Noah (NOTE: In the real game, "Twin-Headed Thunder Dragon" is a Thunder-Type monster, not Dragon-type), but Noah uses a brain-washed Mokuba as a shield to protect himself. Seto calls off the attack.