Scavenging Ooze provides excellent utility against graveyard-focused decks like Azorius Oculus while shoring up the deck's matchup against red burn strategies by gaining life
But this is the perfect card for Golgari commanders, whether it acts as a combo piece for a deck like Grismold, the Dreadsower or just as utility
Considering that Lifegain is plentiful enough in black, Necropotence can quickly cause its player to grab the lead and run away with it entirely
Why wouldnt you want that
A token deck typically wants to create a large number of creature tokens, then either focuses on increasing their power and attacking with them to win the game through combat damage or using these large numbers alongside payoff cards to win the game through card effects
A colorless combo any deck can run combines Wurmcoil Engine, Nim Deathmantle, and Ashnod's Altar to make infinite tokens and infinite mana