For decks to farm each Legendary Duelist, check the links below.
Each farming deck generally do the same thing, which is to deal at least more than 5,000 or 9,999 points of damage. You can go with one of the methods below if you have the required cards to use.
This method uses Gravekeeper's Vassal and Union Attack to increase Vassal's attack to more than 5,000 and deals effect damage for the extra bonus points. Having 2 Union Attack is always better than just using one to achieve "Over 9999 Damage". If you only managed to get 1 Union Attack, you can use Spell Reclamation to re-use it.
Cú Chulainn the Awakened is a ritual monster card with an attack that can be easily increased through cards like Ritual Weapon and/or Blue-Eyes White Dragon. Although his effect only lasts for 1 turn, one turn is good enough since it can be used on the last turn to deal direct damage through Secret Pass to the Treasures.
This card can increase it's attack by 1,000 each time it destroys an enemy monster. It is much more trickier to use than Millennium Scorpion, since summoning this card requires an already face up Wicked-Breaking Flamberge - Baou on your side of the field that is equipped to a different monster, and Guardian Baou itself starts at a very low attack of 800.
This card is available to purchase from the card trader. Victory Viper also has the ability to permanently increase its attack power indefinitely when it destroys an opponent's monster. You can also use the support spell Power Capsule to speed up the process.
With the card Shattered Axe, exclusively from Yugi Muto, you can combine it with Reverse Trap to have it be increased for a turn. Since it adds up every single turn, this will stack up faster compared to the other methods. Use either Enemy Controller + Shooting Star Bow - Ceal, or Jowls of Dark Demise to take control of that monster so you can direct attack. This only works if the equipped monster doesn't get tributed/destroyed, otherwise, you can use Tailor of the Fickle to equip to a different monster.
Each rock monster in your graveyard is equal to 700 attack, so 15 rock monsters is enough to reach the highest damage bonus, giving you at least 5 cards in your deck that you can bring for support cards. You can also bring less rock monsters and use Gift of the Martyr to reach the threshold instead, using Des Kangaroo + The Dark - Hex-Sealed Fusion to get Master of Oz or through Mystical Beast of Serket. Also usable with Gravekeeper's Vassal and Union Attack.
Using a plant type deck, each plant monster in your graveyard will increase your plant monster's attack by 300. While it's lower than some of the attack increasing cards, if used with Talaya, Princess of Cherry Blossoms, you only need 8 plant monsters in the graveyard to reach over 5,000 attack. This can be used with Gravekeeper's Vassal and 2 Union Attack to reach over 10,000 damage.
The Unhappy Girl can stall the duel with Tea's Holy Guard skill.
Most monsters LD uses are effect monsters. The angel will make most of their monsters ineffective since they can't use their abilities. Protect him with cards like Riryoku Field to make sure it doesn't get destroyed.
|Titan Showdown||Lower your LP to trigger the condition and use a high attack monster to reach more than 5,000 or 10,000 damage.|
|Sorcery Conduit||Mainly to get Mythical Beast Cerberus into your hand.|
|Draw Sense: Low Level||Used to get important low level cards to your hand like Mythical Beast Cerberus, Cat's Ear Tribe, or Spirit Ryu.|
|Draw Sense: LIGHT||Alternative to Sorcery Conduit when you want to get Mythical Beast Cerberus to your hand.|
|Restart||When you need a couple of good cards in your starting hand.|
|Holy Guard||Necessary skill for The Unhappy Girl farm decks.|
|Used with Union Attack and Secret Pass to the Treasures, can inflict over 5,000 or 9,999 effect Damage.|
|Easy to summon with Insect Imitation and can keep increasing attack every time it destroys enemy monster.|
|Accumulates ATK points by paying 500 LP every standby phase depending on the top card of your deck. Works well with Draw Sense: EARTH.|
|Deals double damage based on it's attack, which can be increased using Riryoku from other monsters with high attack or other spell cards.|
Mythical Beast Cerberus
|Increases attack by 500 for each spell card used. In a deck with 19 other spell cards, Cerberus can reach more than 10,000 damage easily.|
Blue-Eyes White Dragon
|Often used for tribute summoning bonus points or to be used with Riryoku to boost another monster's attack.|
The Unhappy Girl
|Helps to stall a duel with the Holy Guard skill. Usually used alongside with Gravekeeper's Vassal, Blue-Eyes Ultimate Dragon and Union Attack.|
Cú Chulainn the Awakened
|Summoning a ritual monster card already gives some bonus points, but this card can also reach more than 5,000 damage by using Ritual Weapon and Blue-Eyes White Dragon|
Summoner of Illusions
|An alternative way to get a strong high attack fusion monster like Blue-Eyes Ultimate Dragon by only bringing 1 card instead of 3 Blue Eyes and a polymerization.|
Mystical Beast of Serket
|A great card useful to summon monster from your extra deck, with the used of Celestial Transformation and Temple of Kings.|
Master of Oz
|Master of OZ can be used as substitute to BEUD, since Ultimate Rising pack is already discontinued.|
Blue-Eyes Ultimate Dragon
|Used to boost other monster's attack with Riryoku or to deal more than 5,000 damage with some spell cards.|
Prometheus, King of the Shadows
|Good in a dark deck that can reach over 5,000 attack if used on the last turn.|
|Can be used in any deck with a lot of monsters to get high attack. Use with Gravekeeper's Vassal with double Union Attack, or with Titan Showdown skill.|
Great Maju Garzett
|Only increased based on tributed monster's base attack, but if you can summon multiple monsters with high attack then this is good.|
|Performing a fusion summon gives 400pts.|
|Increases attack for ritual monsters, mostly used for Cú Chulainn the Awakened to reach more than 5,000 damage.|
|Allows for damage that is equivalent to a direct attack, or to increase your attack by sapping the attack of your other high attack monsters.|
|Lower your LP to get low LP bonus and combeback bonus. Also used to remove Joey's Time Magician.|
Shard of Greed
|Speeds up the process of stalling the turns to get to 0 cards left in deck faster.|
Secret Pass to the Treasures
|Allows some monsters, like Cú Chulainn, Piranha Army, and to be able to do direct attack that turn.|
|Used with Gravekeeper's Vassal so it deals effect damage and can finish off the opponent.|
|Allows for some control of your LP to reach 100 LP or to heal opponent for comeback victory.|
|Heal when needed or to decrease LP for comeback victory bonus.|
|To get enemies out of defense position when you want to use Riryoku or to attack them to deal damage.|
Shooting Star Bow - Ceal
|Direct attack or decrease enemy's attack with it's effect.|
Gift of the Martyr
|A great card, can be used as substitute to Riryoku, be aware that it only adds the original attack of the destroyed monster.|
Temple of the Kings
|Besides being used as a requirements to Mystical Beast Serket, the other effect which trap cards can be activated the turn they're set are helpful in most farming decks.|
|One of the key cards in most farming decks. Alongside Gravekeepers Vassal to make the final attack and to get the "effect damage only" assestment.|
Windstorm of Etaqua
|Best defensive card that works in a lot of situations.|
Curse of Anubis
|Alternative to Windstorm. Doesn't work against some Legendary Duelist since it only affects effect monsters.|
|Can be used to destroy unsuspecting enemy monsters during their turn.|
Jar of Greed
|Speeds up the process to get to 0 cards left in deck faster.|
|A counter to Enemy Controller when going against Kaiba.|
If dueling level 40 Legendary Duelist is difficult for you due to lack of cards, you can always farm the LDs at level 30 instead. An easy deck to make is to simply put monsters with 1600 attack or higher level 4 monsters that are glossy and/or prismatic and perform some tribute/fusion/ritual summons for some extra scores. Being able to spam level 30 LDs with a consistent high score is better compared to getting only 3,000 or 4,000 score against level 40.