I have taken down crota HM in 2 swords on countless occasions. I can honestly say that I'm in the #2swordcrew
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There is no need to down him 3 times. You can kill him in 2 swords (hard mode) by doing him 2x 6 with R1+ R2. You have to have the right timing to cancel the animation. I've never seen any american videos but there was a French group who did this 1 month ago, and it works :).