Other black creatures you control get +1/+1.
Other green creatures you control get +1/+1.
At the beginning of your upkeep, you may create a 1/1 black and green Worm creature token.
8/1/2008 The abilities are separate and cumulative. If another creature you control is both of the listed colors, it will get a total of +2/+2.
8/1/2008 Since the token is black and green, it will get +2/+2 from Creakwood Liege as long as the Liege is on the battlefield.