Whispering Madness is a rare Sorcery card from Commander 2016 (C16), collector number 229. Current market price: $3.70, TCGplayer market prices via Scryfall.
Each player discards their hand, then draws cards equal to the greatest number of cards a player discarded this way. Cipher (Then you may exile this spell card encoded on a creature you control. Whenever that creature deals combat damage to a player, its controller may cast a copy of the encoded card without paying its mana cost.)