MTG Salvation

Y u no Martial Coup?!

Also, the new Secure the Wastes is perfect here.

I don't know what you should take out, though. Maybe Sphere of Safety? You already have Ghostly Prison, Propaganda, AND Moat... of the 4, Sphere is the weakest.

You've got plenty of counters/removal. Actually, I'd take out Mindbreak Trap. Yes, it exiles spells, which is nice for removing things you don't ever want hitting the field, but don't discount the effecacy of tempo-counters (counters that aren't necessarily permanent, but hinder an opponent's major plays... like Remand or Memory Lapse). Your opponent has lost the element of surprise, and other opponents might be more willing to gang up on him before he tries to cast the same thing again. Besides, 4 for Mindbreak Trap is a little steep for my tastes.

15 Stick-able instants are more than enough.

You don't need O-Ring; you've got instant removal, which is always better. If you felt the need for exile-removal in enchantment form, go with Detention Sphere, since it at least has the possibility of also taking out swarms. Like O-ring, D-sphere costs 3 and can be recurred with Sun Titan.

Keep Mobilization. Tokens are good in Ertai. The cost to produce each token is a little much, sure, but it's a mana sink -- for when you didn't have anything to counter in a round about the table. It's there to ensure your mana is always getting you value.

Crawlspace is a little less necessary. You've got plenty of attack-deterrents already; I don't think another will help. If someone is intent on hitting you with creautres, **** his **** up. Ruin his board. Combo him out. Whatever strikes your fancy. Keep in mind, you have a lot of control over the creatures on the board thanks to Grave Pact and Martyr's Bond. If no one has creatures to attack with, why bother trying to protect yourself from attacks, y'know?

Keep Mobilization. Tokens are good in Ertai. The cost to produce each token is a little much, sure, but it's a mana sink -- for when you didn't have anything to counter in a round about the table. It's there to ensure your mana is always getting you value.

Crawlspace is a little less necessary. You've got plenty of attack-deterrents already; I don't think another will help. If someone is intent on hitting you with creautres, **** his **** up. Ruin his board. Combo him out. Whatever strikes your fancy. Keep in mind, you have a lot of control over the creatures on the board thanks to Grave Pact and Martyr's Bond. If no one has creatures to attack with, why bother trying to protect yourself from attacks, y'know?

Suggestions:
Ophiomancer: good snake-maker. Synergistic with Ertai. Good "rattle snake" card...
Phyrexian Arena: I have a hard time not putting this in every deck containing black ever.
Dictate of Erebos: Strictly better than Grave Pact in a 3 color deck. Only item of concern is curving into your commander, but this is one you'd likely use after you cast him anyways.
Seal of Cleansing: synergy with Ertai, good rattlesnake, I'd run this over Disenchant.
Seal of Removal: You may or may not want to run this, but again it is a good rattlesnake card (people hesitate to attack you), good utility, synergy with Ertai.
No Mercy: people sometimes don't like losing attackers.
Silent Arbiter: Great Pillowfort card.
Mystic Remora: auto-include in blue, synergy with Ertai.

Cuts: This is the worst part of deckbuilding. I hate cutting.
Disenchant: if you run Seal of Cleansing
Norn's Annex: This is a great pillowfort card, but I would rather have Dictate of Erebos, Seal of Removal, or Ophiomancer
Crawlspace: for Silent Arbiter since the arbiter can feed Ertai.

Also, it would be hilarious to run Dovescape.

Cut:

Fog Bank: You've got plenty of better pillowfort in there already. You don't really need Fog Bank.
Utter End: You've already got Vindicate, and Utter End is on the expensive side for spot removal. Rather than use 4 to exile it, I'd rather use a bounce spell to throw off their tempo for using the problem-permanent.
Containment Priest: Too specific of a hoser, unless there's a serious problem of cheating creatures into play in your meta. I never saw the appeal of it.
Night of Souls Betrayal: It costs 4... and it could kill your token army... I'm not too sure about this one, but if you're using it in a clever way that I'm just not seeing, then you should keep it. If it's just there to hose, you should take it out for better things.

Counters:

Besides Memory Lapse and Remand, there aren't a lot of good 2-shop counters. Sure, these aren't hars counters, exactly, but they do set your opponents really far behind if they'e trying to drop fatties or make major plays. Trust me, a well-timed soft counter can screw up a combo or ruin someone's battlecruiser plans. Plus they can totally be imprinted on Isochron, so they effectively become hard counters at that point.

One you get into 3-drop territory, it can become difficult on the colour requirements. Still, Render Silent and Undermine have always had a little place in my heart.

To Add:

Swords to Plowshares: I saw PtE, but not its older brother.
Claws of Gix: Free sac outlet. Lets you hit any permanent, which combos well with Martyr's Bond.
Skullclamp: Don't know why you have swords in over this. Doing tokens? Use the Clamp.
Academy Rector: Even without Omniscience, there are enough necessary enchantments to warrant it.
Replenish: Because someone's gonna kill your shiny enchantments eventually.
Gate to Phyrexia: Artifact kill on a stick that doubles as a sac outlet. Such a handy card.
High Market: Sac outlets with Grave Pact/Martyr's Bond let you make people sac things on your time.
Vampiric Tutor: If you can afford one, it's worth having. Search for *anything*...
Mystical Tutor: Lets you search for your main answers, like board wipes and counterspells/spot removal. Also, you can set up the pseudo-miracle with Terminus, to handle their creatures on the cheap.

Low-CMC mana rocks. Not the crazy 0-drops or anything, but Sol Ring and maybe some of the Talismans.

More counterspells. I would at least include Memory Lapse and Remand because they're annoying. They're also stupid-cheap (CMC), so there's even more reason for you to add Isochron Scepter. (If you do, can you imagine Vampiric Tutor on the Stick? ^_^)

Consider Taking Out:

Frozen Aether/Kismet: 4 is a lot for what they do. If you *must* include this effect, though, just use one of them. If you start the second one while you already have one (in play or in hand) it's a total dead draw, since their abilities don't stack.
Planar Cleansing: I reckon it's not going to be too hard to have a good board position with this build, so having too many board wipes isn't good. I'd give for quality/versatility over quantity. Austere Command is better in the 6-drop wipe slot for the main reason that you can choose what stays on the board.
Wrath of God or Damnation: Again, you probably don't need both. Plus, you're trying to make creature tokens, so killing off your army/sac fodder won't do you any good.

Okay, that's all I can think of for now. If I recall anything else that I remember about the deck, I'll let you know.