I played against three green decks that all had [[Lead the Stampede]]: what I saw it do is DRAW five cards and reveal the creatures. Pretty nice for 3 mana. If you are not the kind of person to exploit broken cards, stay clear of the entire game until it's fixed.
Bug is apparently known: https://feedback.wizards.com/forums/918667-mtg-arena-bugs-product-suggestions/suggestions/42176071-lead-the-stampede-drawing-all-5-cards
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