First off, let me ask you read the entire first post before replying. I have got alot of help with advice about restarting and using their strategy, and switching from Air version to Nydus version. That's not the case here. please read it all before you reply. Thanks. (and thanks cacho for the video)

------------------ original post ---------------

I just can't seem to get through this Mission on brutal before I am overrun. I have the Strategy Guide for sc2, but the strategy only works for Casual/Normal. I read up on YouTube about which strategy many of them used, but sadly none of them work for me.

I have no Nydus worms to worry about, just the Air units and of course the Leviathan.
I have all the Mercenaries.

Research upgrades:

• - Vandium Plating (hp +5%)
  
• - Strike Turret (Automated Turret on bunkers)
  
• - Micro-Filtering (Vespene Gas 25% faster)
  
• - Perdition Turrets (automated Flamethrower Turrets)
  
• - Automated Refinery (Refinery no longer require SCVs)
  
• - Hercules
  
• - Science Vessel
  
• - Regenerative Bio-Steal (Vehicles/Ships regenerate hp)
  
• - Tech Reactor (Combined Tech Lab & Reactor)
  
• - Psi Disruptor (Slows Zerg Units)
  

Armory Upgrades:

- Base -

• -- Bunker -
  
• --- Projectile Accelerator (+1 range)
  
• --- Neosteel Bunker (+2 slots)
  
• -- Missile Turret -
  
• --- Titanium Housing (+75 life)
  
• --- Hellstorm Batteries (Secondary Attack AOE)
  
• -- SCV -
  
• --- Dual-Fusion Welder (x2 Repair)
  
• -- Terran Building -
  
• --- Fire-Suppression System (repairs 50% life / buildings no longer burn)
  
• --- Orbital Command
  

- Infantry -

• -- Marine -
  
• --- Stimpacks (-10 hp, +50% faster)
  
• --- Combat Shield (+10 life)
  
• -- Medic -
  
• --- Stabilizer Medpacks (25% faster, 33% less energy)
  
• -- Marauder -
  
• --- Concussive Shells (slows units)
  
• --- Kinetic Foam (+25 life)
  
• -- Reaper -
  
• --- G-4 Clusterbombs (Anti-Personel Charges)
  

- Vehicles -

• -- Goliath -
  
• --- Multi-Lock Weapons System (Air & Ground weapons fire at the same time)
  
• -- Siege Tank -
  
• --- Shaped Blast (75% less friendly fire)
  

- Starships -

• -- Medivac -
  
• --- Advanced Healing AI (heals 2 units at once)
  
• -- Viking -
  
• --- Ripwave Missiles (AOE ability)
  
• -- Banshee -
  
• --- Cross-Spectrum Dampeners (cloaks twice as long)
  
• --- Shockwave Missile Battery (multiple missiles in a line)
  
• -- Battlecruiser -
  
• --- Missile Pods (AOE Missiles)
  
• --- Defense Matrix (Shield that absorbs 200 dmg)
  

- Dominion -

• -- Spectre -
  
• --- None
  
• -- Thor -
  
• --- 330mm Barrage Cannon (AOE, Stuns)
  

Some might think I picked the wrong upgrades, but I like what i have, and I don't feel like going back and replaying just to try and make the mission easier. Air version is harder IMO as is, plus with no hive mind emulators, No Viking range upgrades, No Ghosts this mission really becomes complicated. Several strategies fail.

Strategy One: Get the tank on higher ground in 4 points with turrets to fend off waves of units, using viking to fend off broodlords. Eventually you are forced back because too many waves flank you from all sides.

Strategy Two: Pull back early, and wall up behind perdition turrets, Missile Turrets, and Siege Tanks grouped up while using bunkers and viking to protect the Artifact. This seems to work somewhat better from the first one, but in the end the artifact is what gets destroyed by broodlords since siege tanks cant hit air units. (thus why this is used in the Nydus version only)

Strategy Three: Mass building using tech reactors to outnumber the Zerg. Marines, Thors, battle cruisers, to wipe out diff bases making it down 2 lanes that attack. This strategy works well enough but in the end your out of resources and you get overwhelmed before you can kill all of the zerg bases.
I really could use some advice, I beat hard mode some time back before 2.04 brutal seems to be unbeatable for the moment. I have tried every day now since and I am now looking for some advice.

Hm... It's been some time. But I'll try to remember some pointers.
As far as I can remember the mission isn't different from any other defense mission, but you'll need to execute everything perfectly - you gotta save/load whore.
- max your income, you'll need every penny as soon as possible.
- on both sides: Bunkers (like 5?), tanks (like 7+?), SCVs (like 3-4?) on autorepair, maybe medics (like 3) to keep scvs alive
- turrets everywhere, especially on the middle plateau. I think you even need some in the back and sides.
- mimimize losses, replace bunker/tank losses asap
- have as many BCs as possible to help out against stronger waves and air waves.
- reload if you lost more than a couple units/tanks
- save when kerrigan comes. If she gets too many units with her super powers it's gg
- UPGRADES! Air, mech and infantry attack mostly. (Yes you need them all)
- also tech. stim, range, bunker upgrades, slow dunno what else you can. Everything helps.
- apropos tech... isn't there something to slow down zerg? Research that. You won't have the time to properly mind control stuff. But if you got the skills, make sure you mc air units. Those usually don't die and thus will be actually helpful for more than 1 wave.
- use the mercs wisely. Marine mercs in a bunker that is most likely to always shoot at a unit, but isn't dying all the time. Banshees shooting from the cliff. Transformer guys wherever needed (mobile def). That merc BC owns; put it in the heat - it can take a beating and does high dmg.
- patience. Learn from your mistakes. Check the units that breached your def and adjust. Remember where and when a deadly wave comes and plan ahead the next try.

I've personally won it on Brutal, so yes it's doable. You can post your specific doom scenario (how/when you lose), or a replay and I might be able to help you out more specifically.

My run of All In from my LP.

Make a second Orbital Command immediately, quick-build it with extra SCVs.
Saturate early. Get the automatic extractor and tech reactor researches if possible.
Use the early BCs and Marines at the artifact to fortify the north passage while you build defences and siege tanks at the west passage.
Build a fleet of Vikings to take on air units. You should get rid of Nydus Worms because those are much harder to deal with than air units.

It's possible. I barely won on my playthrough but I messed up a lot and it's fairly easy to work with once you grasp the winning strategy.

Take a look at the previous first post with those settings, some pointers were stuff i already do as a basic standard, while others are not accurate do the specific mission itself.