Marai, Life Giver

You may exile creature cards from you're hand, paying their mana cost minus up to 2 coloured mana. Cards exiled this way may be put on the battlefield at any point, costing no mana.
At the beginning of your upkeep, you may pay {x}, if you do create {x} black 1/1 zombie tokens. {x} must be lower than the amount of creatures Marai has exiled.
Life is fragile, I won't mess up.