Back draft can be done with any drafting method.
Instead of the drafting a pool for your self, you draft a pool for someone else, trying to make as bad draft pool as possible.
Normally this involves trying to get useless cards, trying to get cards that do not work with mana curve and cards from all the colors.
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https://mtg.gamepedia.com/Back_Draft
What would be the best draft format to back draft? I think my favorite I have played was back drafted reject rare draft.
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