Yay! A non-restricted version of Flash! Sure, it's a little more expensive than Flash, but it lets green get a solution out really quickly. Your opponent has a vital piece of a combo out and is close to going off? Sounds like you need a Woodfall Primus right now. Getting the smackdown from a big creature and need a blocker? Surprise! Progenitus decided to join the party a the start of a declare blockers step. Finally, if you need to lay the smackdown on someone, a good ol' Worldspine Wurm seems like a great choice. Now, an issue with this card is the double green mana which makes it a little more difficult to splash, but it really does need those two symbols in order to balance it. It also only lets you put a green creature into play, so multicolour decks may be left stuck staring at a great non-green creature that you'll have to play.
Pros: Pseudo-Flash for green
Cons: Green creatures only