I figured the best way to capture Green and Black was to acknowledge that the creatures created by one are then destroyed by the other for gain. That's where the wacky first ability comes from, as you're creating creatures (green) that are meant to be sacrificed (black). You don't necessarily have to sacrifice the token itself, so you can fill your graveyard with actual creature cards for the final ability or you can use this ability in conjunction with the second ability to push a 2/3 through once the smoke has cleared.
The second ability obviously came from Consume Strength, though I changed it slightly so that you could target the same creature with it (if for some reason you wanted to). I can't come up with a reason to do this presently, though I don't like adding restrictions in a world with Johnnies.
The last ability is straightforward because I decided the deck would need a kill condition. It's been clearing the battlefield, so life loss was a shoe-in. It could get out of control and game winning if used properly or be completely useless if your opponent has any sort of graveyard empty effect. Black and green are linked by red, so it seemed appropriate to leave a little up to chance.
Ultimately I wanted the first ability to represent the general chaos of nature and death (with the weakest on each side likely being the one to die each turn) while the second ability showed the predatory links of black and green and the final ability twisting life and death as the planeswalker reaps the benefits of a prolonged and bloody battle.
Anywho, it was fun making cards again. I haven't made one for public posting since I played VS, so it was nice to bust out the photoshop again. I realized I botched the wording on the last ability (it should say "his or her graveyard" instead of "their graveyard" to match the template), but honestly I'm sure Wizards will end up making that change eventually as it frees up space for more text. In any case, making her step out of the card was fun!