+1: Target land you control becomes a 4/4 Elemental creature with trample. It's still a land.
+1: Untap up to four target Forests.
−7: Search your library for any number of basic land cards, put them onto the battlefield, then shuffle your library. Those lands become 4/4 Elemental creatures with trample. They're still lands.
7/18/2014 The type-changing effects of the first and third abilities don’t have a duration. They last indefinitely.
7/18/2014 If the land targeted by the first ability entered the battlefield this turn, it won’t be able to attack and its activated abilities with in the cost (including its mana ability) can’t be activated (unless something gives it haste). The same is true for the lands put onto the battlefield with the third ability.