I have a deck here: http://deckbox.org/sets/65702

Any suggestions?

I strongly recommend Crystal Shard and Erratic Portal in this build. They can be used both offensively and defensively to either bring back your utility creatures (e.g. Wood Elves) or allow any one of your tiny creatures to block fatties and live (provided the fatty doesn't have trample). It can also be used to keep your opponents mana in check as they are often forced to keep two mana open to play around one of these artifacts.

After that I recommend finding room for Eternal Witness, Man-o'-war and Coiling Oracle. The first two should be fairly obvious but my reasoning for the last is a little hidden. Essentially, Momir Vig, Simic Visionary + Crystal Shard + Coiling Oracle is a draw and ramp engine that is incredibly difficult to outlast. If your opponent doesn't shut it down quickly you'll have a fist full of cards and more lands in play than you'll know what to do with; they will be overwhelmed. All the while blocking their largest, non-evasive threat and taking no damage (block with the oracle and bounce to your hand before damage; it was headed there anyway ;))

Please let us know if any of these changes worked for you. I wish you luck!

Thank you! Looks like I need to do some card shopping!

I really like the Crystal Shard/Coiling Oracle combo. I never would have thought of that.

Another possibility which works well with the aforementioned combo is Mystic Snake, if you want a repeatable counter