If you're looking for some good mill cards, I'd recommend checking out Mesmeric Orb , Dreamborn Muse , Extractor Demon , Geth, Lord of the Vault , Grindclock , Increasing Confusion , Jace, Memory Adept , Memory Erosion , Mind Grind , Mindcrank , Sewer Nemesis , Shared Trauma , Sword of Body and Mind , and Traumatize . Most of those are better than, say Paranoid Delusions .

In my opinion, your deck is too split-focused. On one half you're bringing infect creatures to kill them quickly with poison. On the other half you're bringing unblockable creatures to cipher with. The Mimeoplasm can't copy both at the same time. Cipher is effective if you're hitting them repeatedly over a long period of time, but infect wants to win as quickly as possible. I would suggest dropping the unblockable creatures (i.e. Phantom Warrior ) & cipher spells (i.e. Undercity Plague ), but keeping the support evasion (i.e. Aqueous Form ) to help your infect creatures kill your opponents quickly.

Or you could go the other route and keep all the unblockable stuff and drop the infect (except for Blighted Agent and Skithiryx, the Blight Dragon who when copied with The Mimeoplasm can end the game almost instantly. You can throw in Tainted Strike as well for a surprise ending.) Even then I would cut the Cipher stuff that isn't particularly strong. I'm not a fan of Hidden Strings , Last Thoughts , or Mental Vapors for example. Mask of Memory , Mask of Riddles , and Specter's Shroud don't go away when the creature dies, and are cheaper to cast + equip. Frost Titan , Prophet of Kruphix , Seedborn Muse and Tamiyo, the Moon Sage , or even Mark of Sakiko can have much more relevant effect over time.

Putrefax is a really good infect killer. Pair it with something big.