The converted mana cost for Stinkdrinker Bandit is four. You will need one black mana and three colorless mana to bring Stinkdrinker Bandit onto the battlefield. However, it has an alternative and cheaper Prowl cost. You can pay the Prowl cost instead of the full mana cost if you deal combat damage during your turn with a goblin or a rogue creature. If you do, you only have to pay one black mana and one colorless mana.
What does Stinkdrinker Bandit do in the first place?
Think of the Stinkdrinker Bandit as a support creature. In a normal deck, you may want to have about two Stinkdrinker Bandit cards on hand. Stinkdrinker Bandit gives your rogue creatures +2/+1 until the end of the turn should they attack and go unblocked. This acts as support for aggressive deck users. For this reason, you want to build around goblins and/or rogues.
One card comes into mind which can be used with the Stinkdrinker Bandit. That one card would be known as the "Weirding Shaman." For one black mana and three colorless mana, you can use Weirding Shaman's ability to sacrifice a goblin and create two 1/1 black goblin rogue tokens. In a sense, this is like "Vampire Bats" in which you can sacrifice one bat token to create two more bat tokens.
You can create an army of goblin rogue tokens with Weirding Shaman. With an army of goblin rogues on your side, you can attack. In this respect, your opponent will not be able to block all of them. S/he will have to depend on a spell such as "Day of Judgment," "Damnation," or "Wrath of God." For those that are unblocked, they will get +2/+1. A bunch of 3/2 creatures can overwhelm an opponent. In this respect, you have dealt the opponent much damage for the most part.
Overall, the Stinkdrinker Bandit is an impressive card provided that you build around goblins and rogues. If you do, you can attack aggressively with your rogue creatures. With the right combination of cards, Stinkdrinker Bandit becomes an incredibly value support card.