I don't quite see a specific theme to your deck apart from ramping into big creatures (which is fine, really) and maybe a small sacrifice theme. If you really want to take advantage of the sacrifice theme, might I suggest Kresh the Bloodbraided as a replacement general along with Butcher of Malakir, Grave Pact, and token-generators like Awakening Zone, Deranged Hermit (this might be a bit pricey), and Thopter Assembly? Kresh can get pretty scary after awhile since he grows every time a creature dies.
As a final tip, remember that most EDH games tend to be free-for-all / chaos, so one-for-one spells like Terminate, while still good, aren't as good when you have multiple opponents with permanents you want to get rid of. That being said, recursion/reusable effects (e.g. Haunted Crossroads, Volrath's Stronghold, Regrowth, Phyrexian Reclamation) and effects that target multiple permanents and/or opponents (e.g. Earthquake, Syphon Mind, Fleshbag Marauder, etc.) help you get more mileage out of your cards.
My EDH decks all run at least 1 infinite-loop combo for when games go long, but at the same time, I don't immediately go for the combo. As such, I prefer spells with more versatility/usefulness. Looking at your Dracogenius list, you might want to consider some hard removal like Aftershock and Magmaquake to keep you alive in addition to your counterspells.
Interesting take on Thromok. How are the eldrazi spawn guys working for you? I thought about running them, but decided against it and went with a minor goblin theme instead (i.e. Beetleback Chief, Siege-Gang Commander, Goblin Marshal, etc.), along with a few other token generators like Deranged Hermit.
Overall, our decks look pretty similar except for the fact that you're running way more devour guys than me and I'm running more removal/ramp/utility spells. I never find myself needing anything more than Skullmuncher, Predator Dragon, and Mycoloth in terms of devour-type creatures so I'm kinda curious how useful those other guys are that you're running.
Felidar Sovereign and Test of Endurance only work at upkeep, so if he's playing it and it goes around the whole table with no one removing it, your group probably isn't playing enough removal.
This.
Maybe I just like being able to blow up my opponents' permanents, but I'd like to thing every deck should have ways of dealing with annoying permanents. There's removal in every color for these types of things.
Mostly, Thromok decks just pump out a bunch of tokens and win with Overrun-type effects or by sacrificing some/all of them to Thromok and either attacking people to death with general damage or Flinging Thromok at people. I've managed to kill 3 people in a single turn without any infinite combos using Thromok (general damage at one player, Soul's Fire to kill another one, and then Fling to kill the last) multiple times and the deck can honestly win out of nowhere.
I think it's kinda hard to make a good "midrange" deck in EDH since controlling things early mostly involves land destruction, discard, and blowing up mana rocks - 3 things that are fairly hard to do in your typical chaos game. Best you could do is maybe out-ramp other decks and play your fatties before them while blowing up theirs, in which case ETB creatures like Shriekmaw, Big Game Hunter, Woodfall Primus, and Bogardan Hellkite may be best. Personally, if you were going for an ETB-theme, I'd go GW with black or red for creatures with more aggressive/destructive ETB abilities.
Tokens with Trostani, Selesnya's Voice or Rhys, the Redeemed? Spell/creature copying with Riku of Two Reflections? I've seen Riku decks Warp World 6 times in succession on the same turn (it was stacked in the Riku deck's favor because it played a bunch of token generators for added permanents and basically won with a flipped over Fervor /haste enabler + Craterhoof Behemoth)... If you really wanted to just warp the game state and not necessarily win, try playing a group hug deck with Phelddagrif
You could try going with an Angus MacKenzie Bant control deck. I originally built mine to "play god" (i.e. give people creatures, decide if/when combat damage got through, give/blow up lands, etc.) and had a blast with it. White gives you access to targeted and mass removal, blue lets you counter/tuck spells and draw cards, and green allows you to ramp with the best of em. Plus you get to do stupid things like Rhystic Deluge and Cowardice to lock out [most] creature decks and use the old Aura Thief and Enchanted Evening combo.
Interesting build you've got there. Reminds me a lot of my Grixis Japanese Game Show deck I built a few months back. Same concept (bunch of draw 7's mixed in with underworld dreams-type effects, punish everyone) though I have to admit I originally made my deck to break stalled game states (i.e. people runnning out of cards, one person building up combo pieces undisturbed, etc.) and it eventually evolved into a creatureless control/combo deck.
That aside, I'd suggest the following additions to your deck for general mana fixing and utility:
Chromatic Lantern
Sol Ring (really cheap now after the Commander Pre-Con decks reprinted it)
Command Tower
Temple of the False God
Acidic Slime
Decimate (it's a 4-for-1 if you have valid targets and in multiplayer, you should)
Explosive Vegetation / Skyshroud Claim / Ranger's Path
Ravnica/RtR Shocklands (if you can afford them) - Overgrown Tomb, Blood Crypt, Stomping Grounds
As a final tip, remember that most EDH games tend to be free-for-all / chaos, so one-for-one spells like Terminate, while still good, aren't as good when you have multiple opponents with permanents you want to get rid of. That being said, recursion/reusable effects (e.g. Haunted Crossroads, Volrath's Stronghold, Regrowth, Phyrexian Reclamation) and effects that target multiple permanents and/or opponents (e.g. Earthquake, Syphon Mind, Fleshbag Marauder, etc.) help you get more mileage out of your cards.
My EDH decks all run at least 1 infinite-loop combo for when games go long, but at the same time, I don't immediately go for the combo. As such, I prefer spells with more versatility/usefulness. Looking at your Dracogenius list, you might want to consider some hard removal like Aftershock and Magmaquake to keep you alive in addition to your counterspells.
Overall, our decks look pretty similar except for the fact that you're running way more devour guys than me and I'm running more removal/ramp/utility spells. I never find myself needing anything more than Skullmuncher, Predator Dragon, and Mycoloth in terms of devour-type creatures so I'm kinda curious how useful those other guys are that you're running.
This.
Maybe I just like being able to blow up my opponents' permanents, but I'd like to thing every deck should have ways of dealing with annoying permanents. There's removal in every color for these types of things.
Off the top of my head, here are some cheap/easy options (in all colors) for targeted creature/artifact/enchantment/permanent removal:
Chaos Warp
Terminate
Swords to Plowshares
Krosan Grip
Acidic Slime
Dreadbore
Bant Charm
Duplicant
Decimate
Return to Dust
Relic Crush
Hull Breach
Brittle Effigy
Angel of Despair
Bramblecrush
This doesn't even include sweepers like Oblivion Stone, Nevinyrral's Disk, Wrath of God, and Austere Command.
You can basically play "nice" with hug cards so nobody hurts you until you're good and ready to warp the game state with funky enchantments/effects.
Mostly, Thromok decks just pump out a bunch of tokens and win with Overrun-type effects or by sacrificing some/all of them to Thromok and either attacking people to death with general damage or Flinging Thromok at people. I've managed to kill 3 people in a single turn without any infinite combos using Thromok (general damage at one player, Soul's Fire to kill another one, and then Fling to kill the last) multiple times and the deck can honestly win out of nowhere.