Malicious Spikelump

Mystery (You may exile this card from your hand. At the beginning of your upkeep, each opponent may put it onto the battlefield under your control.)
At the beginning of your upkeep, you lose life equal to the number of creatures you control.
At the beginning of your end step, if you lost 4 or more life this turn, put a -1/-1 counter on Malicious Spikelump.