As well said the guy above. You can even try storm or spiritualism (for otk decks).
Gem discount period (rare, never miss it) is usually a perfect chance to get a play set. Also you can easily obtain 1 from special sets or even use your dream ticket without hesitate. You will never regret it.
There's night beam and galaxy cyclone......yeah yeah I know they are as expensive as cosmic. Konami is a master of milking your money: release tons of backrow but just a few backrow removal in terrible boxes -> profit