This is the second time I've seen you give incorrect advice on what is Standard legal today. Mirrodin Block is still legal until September. The only cards in this deck that aren't standard legal are Mana Leaks, Ponder, Phantasmal Image and Adaptive Automatron as they are all M12 and not reprinted in M13. I like the creature base here, except I'd use 2 more Augurs and take out the Images. I don't know how much copy I'd run, Cackling Counterpart and Phyrexian Metamorph are pretty cool, but I'd try running Indexes, or Unsummon first I think. Up to you though, copying the Master over and over makes sense to me.
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Shock isn't standard legal anymore
I agree with arkillon12, your deck has a distinct lack of creatures for a Mono-Green deck. Scrap your spells, and replace them with Green Sun's Zenith, Champion of Lambholt, Predator Oozes etc. I like Nightshade Peddlers, and Acidic Slimes, late game, if you're not crushing the opponent, giving Predator Ooze deathtouch starts giving you a major advantage, and Acidic Slime's entering play effect is one of the most useful out there. I like Bower Passage and Naturalize (which I see you have side boarded). These are almost good enough for main board, and I recommend you consider swapping creature focused spells with threat removal. Thrun the Last Troll, Garruk (either version) and Tree of Redemption all work really well in this deck. Don't forget a Bellowing Tanglewurm either, full board intimidate is nothing to turn your nose up at. Here's my suggestions, hope they help.
But you can only run a max of four of a single card...
That's probably some sound advice, even cutting it to 2 would be acceptable, an early Stensia is a pretty bad draw, because there's so much dedicated red.
I would rather toss Koth down for 4 and swing with a mountain every turn for 4, rather than spend 5, on the chance I have a Phoenix to fling. Volt Charge is an amazingly good burn card in this deck, as 8 of my 14 Creatures utilize +1/+1 counters with their own abilities, not to mention Shrine of Burning Rage, one of the deck's central cards, uses charge counters. A copy of Koth also is the other reason I keep proliferate, as his loyalty counters can be proliferated too.
I really don't see a need to put in mill that doesn't actually get you a card in hand. There is tons of mill in Forbidden Alchemy, Mulch and Tracker's Instinct. Screeching Skaab is also an early defense before you build up, so I doubt I will put in Dream Twist to take out something useful (Mill is a bi product of almost every other card in the deck). The addition of Labratory Maniac is definitely a good idea though, I don't really know why I cut him from the original build. Evolving Wilds I think I would exchange for Ghost Quarter though. This deck has basically no control, I was debating whether I needed Mana Leaks in this deck or not.
I had one in originally, thinking of scrapping the Accorder Paladins for them
Shock isn't a land, neither is Taste of Blood. Stensia is there because really, there's enough dedicated coloured land, and if there's no cards in hand, you still get to ping 2 a turn just because you have nothing to spend mana on. Don't look at it like, "Stensia" is the priority, and more of a permanent that costs nothing to play, produces mana, and allows you to use up unneeded mana, which you will probably use on other spells and abilities, but in a pinch, it ticks away your opponent's life.
With a self mill deck, I would definitely cut down to 60 cards. You have an additional 13 cards standing between you and victory. Armored Skaab may be a card to consider swapping in somehow, for the extra mill, and a single Memory's Journey in your deck will ensure you are able to return Maniacs to your deck so you can start milling from turn 1. Mirror Mad Phantasm, Jace's Archivist, Blue Sun's Zenith and a copy of Jace himself should be considered as well. A free ten cards off your deck every turn makes this deck go from being fun and joke worthy, to a true competitive and scary deck. Just some ideas for you!
Consider running Timely Reinforcements and/or Geist-Honored Monk. Both are worth what you pay for them. If you wanted you could run Tirel Elspeth too. Run Bonds of Faith instead of Pacifism it's basically the same spell, but has alternative mechanics to utilize. If you have them you should splash in some blue dual colored lands, so you can run Moorland Haunts and Geists of Saint Traft. Just a couple of suggestions for you, If you're still interested in my opinions though, cut down to 60 cards, specifically I'd remove the Roc Eggs and the Shrines, (I don't like either of these spells because they require turns to go by to become useful, and this deck can throw down tokens very quickly). Consider removing a few copies of DoJ too, you're likely going to have a major creature advantage against 90% of your opponents, so only occasionally will a board wipe benefit you. You may even want to sideboard them.