Conqueror's Flail is a mythic Artifact — Equipment card from Teenage Mutant Ninja Turtles Source Material (PZA), collector number 15. Current market price: $2.03 (foil $3.80), TCGplayer market prices via Scryfall.
Equipped creature gets +1/+1 for each color among permanents you control. As long as this Equipment is attached to a creature, your opponents can't cast spells during your turn. Equip {2}
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