This card is really great against token decks. I'm a little hesitant to say it's "great" against tribal decks, as tribal decks are apt to run lord effects that will negate the -1/-1 quite easily, but it can happen tribal decks as well. Against non-tribal, non-token decks however, this is pretty garbage to be honest. You might hit one or two creatures with this against those types of decks, but I don't think it's worth it that that point. It's a situationally great card and that's the best I can give it.
Pros: Weakens a specified type of creature
Cons: Pretty useless against non-token/tribal decks