Lucifer, Bringer of Doom

When Lucifer bringer of doom enters the battlefield put two +1/+1 for each creature you control. Whenever another creature enters the battlefield under your control, put two +1/+1 counters on Lucifer, Bringer of Doom. Whenever a creature you controlled leaves the battlefield, remove two +1/+1 counters from Lucifer, bringer of doom. Creatures you control get +1/+1 for each +1/+1 counter on Lucifer, bringer of doom divided by two, rounded up.