A Combo is a combination of 2 or more cards whose effects activate in such an order that allows the result to be different (and potentially more useful) than what would otherwise be normally possible. Sometimes an entire deck can be constructed around a single, powerful combo.
Examples of Combos
This combination allows a face down monster to be banished which would not have normally happened because "Book of Moon" does not banish monsters and "Nobleman of Crossout" wouldn't have had a proper target to select first. It works like this:
- First use "Book of Moon" to place a monster face-down
- Then, use "Nobleman of Crossout" to banish the monster you just placed face-down.
This combo allows you to get a 2800 ATK monster in 1 turn and giving it a 400 ATK boost:
- Summon "Fusilier Dragon, the Dual-Mode Beast" without any Tributes and let it halve its ATK.
- Then use "Forbidden Chalice" targeting "Fusilier Dragon" negating its effect for the turn, returning it to 2800 ATK and also giving it a 400 ATK boost for the turn.
- "Gilasaurus" + "Big Evolution Pill" + Any level 7 or higher Dinosaur-type monster (like "Super Conductor Tyranno")
This three card combo allows you to bring out a strong monster in your very first turn:
- Special Summon "Gilasaurus".
- Tribute it to place "Big Evolution Pill" on the field.
- Finally, Normal Summon "Super Conductor Tyranno" without any sacrifice because of the effect of "Big Evolution Pill".
- Activate "Trade-In".
- Discard "Blue-Eyes White Dragon from your hand to the Graveyard and draw 2 cards from your deck.
- Lastly, use "Monster Reborn" to Special Summon "Blue-Eyes White Dragon" from your Graveyard.
Advantages and disadvantages of using Combos
Although a good way to gain advantage, some duelists choose to avoid combos when possible, especially if they contain three or more cards or steps to them; the rationale here is that large combos take up important resources that could be needed elsewhere (or take up space in the deck that can be utilized for other, more important and useful cards), and the game already includes many Effect Monsters that can do the work of most combos in the game. However, despite this, many of the most popular and devastating decks created throughout the game's history (such as Magical Scientist OTK or Yata-Lock have either included or been based around complex and sometimes long combos, some of which have been completely shut down by the banned list because of their potency, thus rendering the argument against such combos up to personal preference.
Most combos aren't used very often because their payoffs don't make up for the cards that went into making them. Some "fun" players think that games should be played by playing all of their cards at the same time, and generally use cards like Equip Cards, which do increase a monster's ATK, but the monsters that they are equipped on can be easily destroyed with cards like Sakuretsu Armor, Mirror Force and Soul Taker. By the end of the turn in which a monster has been destroyed that had equip spells equipped to it, the player equipping spells to the monster generally has fewer cards in their immediate disposal (their hand, their field, etc.) with which to make a play.
In addition, many combos aren't used because it would be simpler/better for card advantage if a card was used on an appropriate monster. For instance, instead of using Soul Taker to destroy Dark Ruler Ha Des, it might be simpler to wait until a monster was tributed for its summon, and then use Trap Hole to destroy Dark Ruler Ha Des.