Some skills are obtainable as drops from Legendary Duelists from the gate or the ones that appear in Duel World, the skills that you can get are random from character exclusive skills, such as "Destiny Draw" of Yami Yugi and "Harpie's Hunting Ground" of Mai, to common skill drops, such as "LP Boost" skills and "Draw Sense" skills, that all characters can get.
You can fight any Legendary Duelists (LD) to get a chance to drop skills, the easiest ones being Tea Gardner, Weevil Underwood or Rex Raptor. Additionally it's better to duel against the lvl 40s since the chance of getting better cards, gems and skills are higher compared to the lower lvls.
LDs you may avoid
Some Legendary Duelists like Kaiba, Joey, Bandit Keith or Ishizu are known to be difficult to farm, especially if you are using standard farming deck using cerberus.
Be careful on spending Gate Keys
Keep in mind that the colored gate keys, other than white, are used by 2 characters. If you plan on choosing one then make sure that you check the other character to see if you want to get a specific card from them, so that you don't end up using all of that colored key. → Details of Gate Key
Character featured events are chances!
There have been two event featured Pegasus and Yugi Muto in the game, and during those event period, players can challenge them without spending Gate Keys! The GameA website also shows decks to farm those LDs for a limited time with no set skill.
The whole idea is to get the score as high as you can, with 8000 giving 8 cards which is the maximum number of drops that you can get from a single duel, and cerberus is often used due to how easy it is to get attack more than 9999 damage which gives 3000 pts. → How to get a high score
High Score Scorpion
I strongly recommend you to use this deck for the following three points:
No card from booster packs needed.
Can get around 6,000 score against Rex stably.
No skill is required that means you can use any character with this deck.
Basically your Yami Yugi, Weevil Underwood, and a character who has already acquired drop "Draw Sense: Light" skill, can handle a deck with cerberus and put 19 spell cards which includes stop defense works. Their "Sorcery Conduit" skill and "Draw Sense: Low-Level" skill allows you to get the monster to your hand. This is known to be an easy way to achieve a high score. → High Score Cerberus: deck recipe
[Roll 'n' Boost] Can be used each time your Life Points decrease by 2000. Show 1 monster card in your hand to the opponent and roll the die once. The Level of the monster shown becomes that of the die number untile the end of the turn. → Roll 'n' Boost: deck recipe
[Menace from the Deep] Can be used if "Umi" is on the field, and you have a Water-attribute normal monster on your field. That monster can attack your opponent directly this turn. At the end of the Battle Phase, that monster is sent to the Graveyard. This skill can only be used once per turn. → Menace from the Deep: deck recipe
The best would be to add Martyr in deck if you don't have 2 Ruris or even if you do ; it's still a better combo since for Ex: 5000 dmg / 2 = 2500 / 2 = 1250 ; total bonus would be 3750 dmg ; but if you use martyr after ruri the total bonus is 4500 if you take as base the Millennium Scorpion ; also as a trap card using rising energy is better since u get an extra 1500 atk + final delivery system : Piranha Army ( x2 direct dmg ) so if u get a 5000 dmg scorp the total dmg would be ( 800 + 2500 + 2000 + 1500 )x2 = 13600 dmg ; ofc in this case u can drop either the trap rising energy or kill 3 less mobs with the scorp and you still do over 10k dmg ; also please note if u use fusion + ritual as in the above example ; fusion first , ritual second ; so that you have space for piranha army ; also note that yugi lv 40 has 2 kuribos in hand so u need to make him use them up.
wrong and fool : LDs you may avoid are not : Kaiba, Joey, Bandit Keith or Ishizu. but idiot/odion (odiot), how much u farm this odiot, no 1 drop skill u get.. i farm 7x lv40 no any drop skill (cerberush), very very.....