If you're on a tight budget, there's good news waiting if you're okay with damaged cards, as you can pick up a copy for under $20 in most cases
Its odd enters-the-battlefield wording basically makes you sacrifice a swamp when it comes into play, but it does enter untapped and doesnt specify that the swamp must be untapped (unlike something like Everglades)
Take Knock Outs, as appropriate, by using Roaring Moon exs Frenzied Gouging attack, which instantly Knocks Out your opponents Pokmon in exchange for Roaring Moon ex doing 200 damage to itself, Roaring Moon exs Calamity Storm, which does 100 damage plus 120 more if you discard a Stadium card in play, or Roaring Moon TEFs Vengeance Fletching, which does 70 damage, plus 10 more damage for each Ancient card in your discard pile
Now lets jump into my number 10 pick
Here are a few more looks at whats to come
Doc Ocks Tentacles can double as a cheap artifact that ramps up Affinity, and as a way to make your Affinity payoffs more significant