Rampaging Sewer Croc

Trample
{t}, Pay X life: Rampaging Sewer Croc fights
target creature with power X or less. Rampaging
Sewer Croc doesn't untap during your next untap
step.
At the beginning of each of your end steps, if you
paid life this turn, put a +1/+1 counter on
Rampaging Sewer Croc.