Poisoned Sewers

At the beginning of your upkeep, pay {x} mana.
Then, each player chooses loot or rummage. Each player who chose loot discards X cards, and each player who chose rummage draws X cards.
At the beginning of your end step, each player shuffles their graveyard into their library. Then,
each player who chose loot this turn draws X
cards, and each player who chose rummage this
turn discards X cards at random.