Stunted Growth

Once again, the art in this set has been unmatched as whole sets are considered. The whole set is awesome and this card is a prime example.
Technically, 1) green never fails to let me play this before the fifth turn. It never fails. 2) Both players are using very good cards (rightfully), and this always puts me ahead one step for the rest of the game. Green can afford a higher mana curve, and this spell hits them for three to your one.

This may not look that great, but think about it. It's like making your opponent discard three cards from his hand, and then make him wait three turns to get them back! Although it's not nearly as useful in the mid- to late-game when your opponent may be holding one card to put on top of the library, with Rofellos, Priest of Titania, and Gaea's Cradle, casting it on turn three shouldn't be a problem. It also fits perfectly into a mono-green land destruction deck with Plow Under, Thermokarst, Fallow Earth, Tangle Wire, Rishadan Port, Wasteland, the list goes on and on.

Honestly, by the time you're able to cast this your opponent
won't even have three cards in hand. Sure there is a lot of stuff
like elves that can help you cast this early but in all reality this is a late game card.