Aside from being easy to bring out as a two-drop, Scavenging Ooze is prominent in many formats at the moment for both its potential and flexibility as a card.
Being able to exile any card in a target graveyard for a measly is quite deadly in itself because it hoses any graveyard-focused deck. However, its secondary effect of gaining a +1/1 counter and an extra life if it eats a creature is what makes this card dangerous.
Early in the game, Scavenging Ooze is still a decent 2/2 fighter, but it easily becomes stronger as a regular game plays out. Later on, there will definitely be plenty of floating around for Scavenging Ooze to trigger multiple uses of its effect. Plus, you can bet a lot of creatures will exist in the graveyards for Scavenging Ooze to munch on.
In other words, having a fed and beefy Scavenging Ooze later in the game (and we’re talking at least 5/5 stats from its effect alone and with extra life gain to boot) is easy for this card to pull off consistently. When you’re hungry for wins, Scavenging Ooze certainly boosts your chances with its appetite for graveyard cards.