Milling is typically a bad strategy, as you essentially make your own job 3 times harder than it is to begin with. But, it holds the potential for being one of the most amusing strategies and certainly the most rewarding if you can pull it off. A few thoughts:
1) At current the deck is not standard legal. Geth's Verdict is from New Phyrexia which rotated out with the release of RTR. If you're looking for a similar effect, Devour Flesh is available. It's an easier mana cost and would result in them gaining some life, but if you're looking to kill them via mill, that's not an issue. Then again, there are better removal options out there as Devour Flesh could end up only taking out a 1/1 when you're trying to take out a big target.
2) If you're looking to mill the opponent, you really need some better ways to do it. At current you're only sitting on spells that will mill them a few cards at a time. Things like Mind Sculpt can be huge in this case. Similarly, I would look into getting some Consuming Aberrations - as they offer both an alternate win condition by becoming huge creatures AND a means to mill the opponent more. Note that it triggers whenever a spell is cast, not when it resolves, and that cipher spells are cast when the cipher trigger is hit.
3) Sage's Row Denizen is normally not a very threatening card, but when paired with 2x Faerie Impostor. You keep unsummoning the impostors, essentially making a one-mana - mill two effect. Further, any flicker effects could be useful here - although most would cost more than they're worth.
4) I wouldn't rely on cipher nearly as much as you are. Sure, you're likely going to get an extra trigger or two, but in constructed play there are a LOT of ways to deal with creatures and a cipher effect puts a big target on the creature. To the extent that you do put it on anything, Invisible Stalker is going to be your best option.
5) I get that you're just starting out so you might not have the most extensive collection yet, but Spell Rupture is going to be a poor choice most of the time for countermagic, as, to be honest, it requires you to have a creature to have any effect. You could achieve a more consistent effect by simply using Syncopate.
6) You can replace your draw effect with Thought Scour. It's cheap, it draws cards, and works you closer to your goal.
7) Sadly, for any mill deck to have a prayer of being successful, you do need at least 2x Jace, Memory Adept.
8) Aetherize/Cyclonic Rift might be a good options for potential board wipes when paired with Whispering Madness - unsummon all their stuff and then cycle hands. It could even result in a HUGE draw boom/mill if you can keep them from playing the best stuff from their draw.
9) Lastly, I'd consider the Duskmantle Guildmage as a last resort win-condition.
If you'd like to take a look at the mill build I have thought up, it's here: http://deckbox.org/sets/286911.
Good luck!
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