Linear Equation Cannon

Cast this spell only during combat.
Pick a number from 1-6 (X) and choose target creature an opponent controls, note that creatures mana value (Y) then note the number of permanents that creature's controller controls. Perform (X times Y) + Z. If the result is equal to the number of cards in your graveyard mill X cards. Then choose up to X target non-land permanents that opponent controls and shuffle them into their library. If you didn't mill cards this way you lose X life, where X is 2 times the chose