Kaiba and Bukura are the champions of making you want to pull your hair out while farming. Your best bet would be to keep farming him at level 40. Ra Stall using Golden Ladybug, Worm Bait, and Double Summon or Lab Builder with cards like Chivalry, Magnet Force, and Riryoku Field. Try to squeeze in Anti-Magic Arrows to prevent E-Con on the last turn.
^Exactly. I don't know why people get so worked up with farm decks, you can just bring a Beatdown deck and set the multiplier to x3..........The same with events