Maybe get rid of the Llanowar Augurs and throw in some Llanowar Elves for more speed. Boreal Druids also help for speed but aren't as good.
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I forget what the name of the card is but it says that you can make all creatures have -1/-1 or +1/+1. The -1/-1 would just kill off all those 1/1 creatures youre giving your opponents. I'm pretty sure you'd still gain the life for them coming into play (but then dying immediately after resolving). I think its black though, but that shouldn't be a problem for your birds.
Maybe fill the 4 open spaces with Boreal Druid
Viridian* Longbow... sorry. If your looking to make it faster play with Llanowar Elves, Boreal Druid, Skyshroud Ranger or even Rofellos.
What about Heedless One, Wirewood Pride, Ambush Commander? Thornweald Archer is awesome at taking out big guys. Or put Veridian Longbow on him and just tap him to kill guys. Maybe Overrun, but I dont use it in my Elf Deck so I dont know how it'd turn out.
After you play damnation, next turn you might want to play Avatar of Woe to make sure they dont get any creatures in play before you cast Biorhythm.
for defense you might want to try to run Souls of the Faultless, Faith's Fetters, Pillory of the Sleepless (like grifterm45 mentioned). To get your Cauldron faster you might want to try using the Dimir House Guard to transmute for it. He's also a good blocker if you already have your Cauldron in play.
Throw in some guys with Mountain Walk. When you play Magus of the Moon against a lot of decks you'll make your opponents have mountains and wahla!