Cruncher

Tithe Drinker, Sin Collector (sideboard), Pontiff of Blight, Ready // Willing, Blood Baron of Vizkopa should be working good with this deck, so far I don't think you need to add a third color.
With Pontiff you could go for Lingering Souls, being able to cast for twice the extorts is nice and with the Pontiff the souls give a ton of triggers. If you go this route you could also add Maw of the Obzedat... then again that would be a lot of change :D

A few cards switched around, less Aggro.

Add Slaughterhorn / switch it in with Rubblebelt Maaka. Easier to scavenge or cast if you need to. Since you need three creatures with Bloodrush to make Signal the Clans work good, try putting the Slaughterhorn instead of something.

Thinking about adding Deathrite Shaman and Falkenrath Aristocrat as well as some main deck removal, some suggestions regarding this?

Yeah I listed it in How to Play as well. Varolz can regenerate once with the Arbor Elf completely free, while Lotleth Troll won't be able to regenerate until your next turn.

Yup, you would just shuffle the Loyalist into your deck this way.
Also before anyone asks, if you have two Storms out, you search your library for two cards with the played type, simple as that.

Good point. But it will do less damage on T3 this way.

The Gatekeepers are actually quite good in keeping you alive, especially with Hold the Gates you have a good defense.
The biggest weakness of this deck are the gates (lol) as they slow me down a turn, also Elixir of Immortality is important as there are only 2 of each gate.

Supreme Verdict is strong but I like that this deck is very cheap, Verdict alone would double the price.

However I realised Cloudshift was missing, with it the Keepers are much better.

Someone in the community of MTGS spoiled him, but he has spoiled a lot of cards meaning he is a reliable source.
Tonight / tomorrow morning the final 40(!) cards will be spoiled, with about 5 black, 5 white and 10 multicolor cards. There could be some treasures among them, even if they are mostly common and uncommon.

Pontiff of Blight
4BB
Extort
Other creatures you control have Extort.
2/7

Might be good?

A tapped creature can't be declared as a blocker and a creature won't tap when it blocks.

The cloak could replace the Dolmen Gates as it also protects your creatures. For the Sword... maybe the Battlegrace Angels.

Two cards to consider:
Sword of Vengeance, Whispersilk Cloak

Some small updates.

Would Gutter Grime fit into this deck? Also there isn't too much to ramp into so maybe you could drop the Elf for more flavor :)

Quick update, changed some cards, improved the mana curve.

Rafiq and Finest Hour are just sooo annoying :D
I'm no exalted expert, but wouldn't Berserk or Chameleon Colossus be nice in a deck where the power of a single creature matters so much?

Also Rancor could add a bit more evasion if you don't draw into the Stalker.

Vexing Devil is definitely not bad with Varolz, if they let you burn you scavenge for one, if they don't you can pump it with something else or just sac it totally free with Varolz, then scavenge it.
Slumbering Dragon could also work, thanks to scavenge he wakes up quickly or is just another nice target.
Also Skullbriar could work nice with this deck, perfect target for the counters or a powerful 2 mana scavenge.

Thanks, I added 2 of them to the sideboard. There was also Mizzium Mortars in the sideboard (now in the main deck), which works perfect with the Seer as it only costs 2 life but kills nicely if overloaded.
Also Electrickery may help in some cases, sideboarded.

Wow I didn't think of using the Dimir Charm to burn even more, nice!
I made a Seer deck some time ago but seeing this use of the Charm I quickly added it to the deck. Maybe you want to check it out http://www.mtgvault.com/cruncher/decks/seer-control/
Since your deck runs white, how about (sideboarding) Sphinx's Revelation? You can never have enough cards with all those low cmcs!