If it were me I would dial back on the number of Birds and Lotus Cobras. Your mana drop doesn't exceed 4 mana, which you can achieve by turn 2 right now. If you opt for harmonize this of course is no longer the case. I might suggest reducing the quantities(which will reduce frequency) but since you are making room for draw engines it should equal out. Personally I would go with the Lens. Its cheap, it gives incentive for them not to block the equipped. Also in contrast to your other 2 cards it doesnt increase your decks mana dependency, and it doesnt reduce toughness making your creature more vulnerable.
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There is an instant just printed in M12 called Hunters Insight that would work as a draw engine without screwing up your flow too bad. Mana drop is {2}{G}.
Lashwrithe could be good in a mono black deck.
Just a thought but what about a precursor golem? your giant growth would pump every golem you had on the board then.
throw in a myr welder and just send the titan forge to the yard, imprint to the welder. 2 galvanizers, 1 palladium myr, and a welder=infinite 9/9's.