My favorite Magic card is Saproling Burst.
I used to run it in a mono-green legacy deck that would tear the pants off most other legacy decks, despite those decks being many times more valuable than my own. Creature generation on an enchantment - yes please!
Also, it was my first foil card.
Rise of the Dark Realms - Cool card, when it works. Too situational, with too high of a price tag, to be effective in this deck.
Cruel Ultimatum - Brutal when you have one opponent; not so much with you have three. You'll want any spell you're spending 7 on to affect everyone.
Backlash - you're using exclusively big creatures - when are you going to want to tap them for this effect rather than smash someone's face with it?
Jace, Memory Adept - He's decent in standard, but he's not enough in EDH. At best, he'll draw you one card a turn, assuming he survives. For 5 mana and access to blue, you can do better.
Afflicted Deserter - too situational, doesn't do much, no evasion.
Jeleva, Nephalia's Scourge - have you found her useful?
Some of those high casting cost sorceries - they each have their use, but you have too many sorceries that will plug up spots where you'd rather be dropping your big fatties.
Some of the targeted removal - as a control deck, it's great to have the ability to remove problematic dudes, but you have a ton of removal. I'd cut some, especially since you're planning on just using one of your big board wipes later.
What would I add? Some control elements, some efficient draw magic, and some way to close out a game.
Rhystic Study - will draw you way more cards than Big Jace.
Control Magic - you seem like you have a steal theme, why not include this one?
Wash Out - might be a solid replacement for some of your higher casting cost spells, but more effective.
Thassa, God of the Sea - she will filter your draws and will give you some inevitability in the form of making your dudes unblockable.
Archaeomancer - you seem to have a ton of spells you like, this will bring some back to use again!
Oblivion Stone - Grixis colors are weak to artifact/enchantments. This solves that problem and is on theme.
Hinder, Spell Crumple, Rewind, Arcane Denial - my preferred counter suite, since they do something in addition to countering a spell.
These are just some ideas. I'd check out many of the decks in this forum with grixis commanders (Thraximundar, Jeleva, Nephalia's Scourge, and of course my Lord of Tresserhorn, just to name a few) to get some other great ideas.
Good luck!
I'm not sure if you plan to primarily be playing 1v1 or a multiplayer game, but since this is in the multiplayer section, I will assume that. You probably will want to cut many "1 shot" effects - cards that you use only once and they're done. Cards I would consider cutting for this reason are: Illusionist's Gambit, Spell Pierce, Duress, Thoughtseize, Inquisition of Kozilek.
Next, I'd adjust your draw suite. Currently, you have a lot of cards that let everyone draw cards. In this type of deck, I would consider cutting those - the problem is that for every card you're letting an opponent draw, you're allowing them to possibly lay down a threat that you'll need to deal with or get closer to a combo. Cards I would consider cutting for this reason are: Skyscribing, Prosperity, Temple Bell.
Next, I'd cut a few cards that I'm not sure will further your strategy or do not work well with the rest of your list. Cards that I'd cut for that reason: Starstorm, Claws of Gix, Skullclamp.
Other cards I'd consider adding: Wash Out, Rhystic Study , Frantic Search, Thassa, God of the Sea, Cyclonic Rift, Toxic Deluge, Kokusho, the Evening Star, Phyrexian Arena, Beseech the Queen, Reanimate, Erebos, God of the Dead, Coffin Queen, Havengul Lich, Grim Harvest, Phyrexian Reclamation.
Good luck!
So in your colors, I might consider forced sac as an option. Butcher of Malakir, Grave Pact, even Fleshbag Marauder. Use the first two with decent sacrifice outlets, like Ashnod's Altar. Good luck!
Spentbullets: I'd try cutting Birds of Paradise if you want to test out Ephara, God of the Polis. The other cards you listed are all great and not something I'd want to cut.
Tog: Interesting suggestions. I'm not wild about Hokori, Dust Drinker. She's a bit too control for my tastes, but if I put in more stax-type elements, I will definitely take a second look at her. Riftsweeper is an interesting idea please let me know how she does during testing! I haven't had a lot of problems with my creatures getting exiled, but I think he's got an interesting ability anyway.
You said you cut your sac lands - do you mean fetch lands? I've found them very useful in terms of hitting my colors consistently, and also, sometimes I run Life from the Loam when I'm expecting the local mass LD players to be present, and I get added benefits from them.
I'm currently very happy with my draw effects. I very rarely have problems losing gas, and the great thing about Roon is that any ETB creature with a draw effect can be flickered for more card draw. I'm considering moving away from my non-creature card draw (Rhystic Study, Sylvan Library), but am hesitant to become TOO reliant on creatures.
Got a lot of games in this weekend, so new thoughts:
I've gotta lower my curve a bit. I got hit repeatedly by Ashling the Pilgrim and didn't have an answer until turn 4.
On the chopping block right now: Burnished Hart, Spine of Ish Sah, Purphoros, God of the Forge, Pontiff of Blight, Jhessian Zombies, Crosis's Charm, and Read the Runes.
I'm considering adding Nevinyrral's Disk, Death Baron, Coalition Relic.
Tried Muddle the Mixture, great card, but that double blue is something that I'm having trouble reliably reaching given my mana base.
I guess in my meta, having a creature's value being dependent on the attack phase is a knock on it's value, versus the value of Courser of Kruphix.
Another value I get out of him in my Roon of the Hidden Realm deck is that I can sandbag lands more comfortably, as mass LD is typical in my playgroup.
Cyclonic Rift. I would probably take out Phthisis.
In Grixis colors (red/blue/black), you are weak to enchantments and artifacts, as you do not have great removal for them. Some answers are Nevinyrral's Disk, Oblivion Stone, and Spine of Ish Sah. You can also recur these with Academy Ruins. Of course, these are all dependent on your budget.
I think she's much better than the other creatures you listed because they all require you to connect with an opponent - she does not. You can benefit from her the turn she hits the table.
For my decks that are ramp-heavy, I'll include her after Oracle of Mul Daya.
As stated above, another benefit is that she's recurrable with Sun Titan and Reveillark.
Edit: Quoted the section I'm responding to, and mentioned recusion.