WhisperingMage

Vector Asp seems cheap for turn 1 but i feel you need to have more card drawing

since you are not running red much at all anyhow...
-4 Snapping Creeper, +2 Overgrown Battlement, +3 Wolfbriar Elemental (not plant but better)
-2 Lightning Bolt, +2 Green Sun's Zenith for your Battlement

you could add a few Ichor Wellspring to draw two cards. will help keep the pressure on the opponent

+1 Garruk Wildspeaker. he is better than Nissa. -1 Fauna Shaman, -1 Nissa's Chosen, and -2 Llanowar Elves so you can add +4 Lead the Stampede. since you have a ton of creatures, that spell will keep a lot of creatures in your hand for playing each turn

check out mine for some ideas http://www.mtgvault.com/ViewDeck.aspx?DeckID=148874

Steel Hellkite is nice but slow and vulnerable for 6 mana. add 2 mana leak cuz your Stoic Rebuttal won't be able to cast for only UU since you might not be able to keep 3 artifacts on the board (high mana cost).

lessen some creatures to add a few draw spells. force of will if you can but you will need to draw moer cards even more. you can attack with the Conclave if you didnt just play the land this turn.

1 less basilisk collar to add a Garruk

you can make the numbers more than 1 so you don't have to repeat again and again. when you are editting, just type the number you want into the box where the 1 is then click the update button of the lower right side

Ascetism 3GG enchantment or Eldrazi Monument 5 artifact will protect your elves. Bear Umbra is nice but Lead the Stampede draws more cards faster. 1 more Cultivate

instead of 4 tunnel ignus, maybe open up 1 slot for Goblin Chieftain? nice deck tho

4 Ichor Rats would be better than 2 and Septic. 1 too many Pistus Strike maybe cuz not many decks play flying creatures. you play with Swamp so add some Go for the Throat instead and let other cards deal the poison. You already have Blightwidow

Is this just a casual deck cuz Rampant Growth is not Standard legal. you could add stronger spells if your are playing Extended. not expensive ones either. add some Slagstorm or removal spells

not terrible.. just dont forget to add a few Slagstorm or other few removal spells to make things easier. Concussive Bolt maybe not good enough, and Into the Core can do double the job of crush. should consider adding more powerful spells

great fun deck. if you played with 61 cards, you could add something else or big draw

add 2 more Acidic Slime would help protect you from troublesome artifacts and enchantments

Besieged has a card called Lead the Stampede. It will really help your deck to get more creatures into your hand. at least double your fun! =)

add a Clone or two. they can help against Titans or make more crabs

-3 Ajani's Mantra, then +3 Rest for the Weary =)

i would -2 Greater Basilisk, then +2 Acidic Slime to handle any opponent artifact or enchantment