Extra Arenas are the most highly abused post-game mechanic, because to 100% the game, you are inevitably going to play all five Extra Arenas, FIVE BLASTED TIMES

Deck List Monsters Dark Magician (3) Ash Blossom & Joyous Spring (3) Apprentice Illusion Magician (3) Dark Magician Girl (1) Magicians Rod (3) Magicians Souls (3) Red Eyes Black Dragon (1) Spells Called by the Grave (1) Soul Servant (3) Dark Magical Circle (3) Magicalized Fusion (1) The Eye of Timaeus (3) Dark Magic Attack (1) Secrets of Dark Magic (1) Traps Solemn Judgment (3) Solemn Strike (3) Magician Navigation (1) Eternal Soul (2) Magicians Combination (1) Extra Deck Accesscode Talker (1) Linkuriboh (1) Link Spider (3) Ebon Illusion Magician (1) Amulet Dragon (2) Imduk the World Chalice Dragon (1) Knightmare Phoenix (1) Knightmare Unicorn (1) Norito the Moral Leader (1) Predaplant Verte Anaconda (1) Dark Magician the Dragon Knight (2) Relinquished Anima (1) Selene, Queen of the Master Magicians (1) The Dark Magicians (1) 4 Handtrap, Quickplay Offensive Aside from the sheer firepower of Quickplay Spells, the arrival of handtraps changed the entire meta of the Yu-Gi-Oh

Putting Lightning Greaves and churning out Rats turn after turn when your commander is out is going to be hard to contend with
Handtraps, Board Breakers & Other Staple Cards Maxx "C" This powerful handtrap can severely limit your opponent's plays
The great thing about Be Prepared being a song is you can exert a character to sing it for free, keeping all your ink open to play another character or two into the open board