This is mostly my speculation based on the changelog of the past few years.
Karax at initial release was an exceedingly hard commander to play.
_ His army has campaign stats but is 50% more expensive. Some of the units DON’T have their unique abilities available by default (Colossus’ fire beam, Immortal’s shadow cannon, Mirage’s Phasing armor, Sentinel’s reconstruction, Carrier’s repair drones).
- In short, his units are more expensive than versus protoss,
- requires expensive research and upgrades to meet campaign status
- note: i said campaign status, not coop status because coop units are generally more powerful than campaign units at max upgrade
_ His static defense are strong as they are now but the research for them are also slightly costlier.
_ His top bar’s researches also cost more to upgrade.
The initial design direction is speculated to divide Karax’s power into 3 main branches.
_ Army focus: Which is the most terrible build considering the cost of his units and the amount of tech research + weaponry upgrade he has to get.
- Unlike other commander who can afford to not upgrade units weapon. Most of Karax’s major damage dealers requires weapon upgrade to be effective in late game. Sentinels are the cheapest units in his arsenal and they are usually amassed in the Sen-Mira build, high-armour enemies shrug off their attack with ease so trying to max out Sentinel’s damage is an incentive. Mirage and Carrier are also countered by high-armour. So his army is forced to upgrade to stay in the game for later stage.
- While labeled as ‘powerful robotic army’. His army aren’t strong specialists or versatile as Artanis or Raynor or Kerrigan at that time (which is before Muta buff and Dragoon buff). None of his land units are reliable anti-air units. Energizers’ tickle beam and Immortal’s 200 damage wonder can’t deal with sky enemies in general which forced player to invest in the air tech tree. The air tech tree while being versatile enough to deal with air and ground units up to certain degree are exceedingly slow both in moving, amassing and damaging as Hybrids, Ultra, Carrier, BC brush off Mirage and Carrier’s peashooters.
- Despite being expensive, his units’ performance never justified their cost and the only units that actually does is the Energizer which can tickle an Ultralisk to death with a K/D ratio of 1 to 20.
_ Unlike the horrible’s robotic army, Karax’s static are generally extremely strong at standing their ground. An well-invested fortified position can soak up a lot of damage with minimal loss which Swann’s couldn’t when his SCVs are being targeted or when siege air units attacking his turrets. They are very well-round. Their set-up speed is top tier, bar none. Can self-sustained without player input. Dealing with swarming comp, long range siegers and boss units very well. Being the jack of all trade, his static aren’t the most powerful but has no weakness.
_ The third branch is probably investing in top bar researches. Unlike the mediocre price of the current stage. His initial research cost for these are borderline cutthroat but they are required however to compensate for the weakness of his standing army.
The development direction for his initial release was probably having a very small group of units with support from the top bar to deal with enemies. This does not work because when you have air enemies to deal with while you only have ground units, your solarite are allocated and spent on air units which forced you to save them up and not using them to help his mediocre army to deal with high-profile ground targets (hybrid, ultra, thor, aberration). The air tree may be working well for him but they are too gas heavy to amass a decent fleet that can defeat an attack wave without loss (anyone here who is familiar with the Lanchester’s law will probably understand why it is hard to keep a small group of units alive) and the solarite will also have to greatly allocated to help his air. When Karax was playing missions that doesn’t require him to aggressively on the offense, he play quite well but map that forced him to move out early as usually bad for him overall. Even the probe push build require him to have an early investment on top bar researches + a good amount of sentinels to play as bait while his probe set up cannons.
Karax at that time has very bad design where his mastery and mission will dictate how well he performs. There were buff and nerf over time to make Karax up to the standard power.
Notorious buff include:
_ general reduction in armor and shield upgrade cost
_ Colossus’s fire beam deal 150 in 5s instead of 100 in 5s (campaign value)
_ unit cost reduced to only 30% more expensive rather than 50%.
The devs seemed to agree with general opinion that Karax was not good though they still stubbornly believe that his good static defense and robust top bar justify the army cost which it isn’t. Karax’s army have the same weakness as Zagara’s, the “unless you have enough units or energy to deal with the wave, you have nothing” problem. This is particularly true for Karax. His Immortal does not attack air and their shadow cannon has terribly long cooldown, accurate usage is very important. His energizers weak air attack made it a blinking target for air army and when he loses gas units it is a major set-back. Though many people also expressed their disagreement that Karax is flawed by saying that his Top bar can cover for his weaknesses which is essentially untrue as the production rate aren’t enough to keep up with an aggressive mission’s demand and even with all mastery in solarite, Karax still struggle while others breeze through.
There is also a notorious nerf in this period which is the interceptor cost 15 mineral. Monk at that time justified the decision as he compare it to the 15 mineral cost of versus interceptor. He was personally called out as coop and versus operate in completely different macro design. While in versus, mineral fields are everywhere and players can boost their income far above that of coop, versus players also has many ways to weaken enemies attack by targeting their eco. The nerf was revoke at the next patch.
Now the current design of Karax seems to be relatively the same as the initial release but moving to another problem. To name a few reasons, his researches and upgrades are cheaper, his army is more durable, Immortal’s shadow cannon deal more damage. The worst thing about this new revamp is the absence of unit cost reduction mastery while in the previous patches, players at 90 mastery can trade static durability with more units (or in a different way of understanding more total damage output).
I believe they must have take in some of the random suggestions (which also includes my opinion) without context and slap it on the patch.
To specify, the discussion was to turn his units into a tough Son.Of.B to provide sight for top bar bombardment. This idea was shot down because many don’t want to play Karax that way as it dumb down his option and builds.
Thus, here we are again with a commander that has no option but to research everything even the useless one to get a strong army while Kerrigan can just max Hydra and omega.
So if they want to keep the price, so be it. I will advise different mean to justify it and to make sure the army is strong enough by itself.
Cost increase to 50% more expensive from 30%.
Armour upgrade give units +0.5 health regen per level
Shield upgrade give units +20 max shield per level
_ Charge deal 16 (+2 per weapon) upon reaching the target
_ For 5s after reconstruction, Sentinel’s damage is increased by 30% and take 20% less damage.
_ won’t attack air
_ they move 30% faster when attacked
_ Shadow Cannon’s cooldown reduced by 2s every time Immortal attack
_ Immortal can switch into AA mode. In AA mode Immortal can’t attack ground but have a weak AA attack, dealing 20 (+2 upgrade) with the same speed and range as their ground attack. Changing mode take 1s. Energizers buff will also speed up changing mode speed by 100%.
Colossus (name changed into Incinerator)
_ Fire Beam dps stack infinitely
_ Incinerator can attack while walking after researching Thermal Lance
_ Incinerator gain the Burning Ground ability by default. Burning Gaze unleash a beam that sweep the area In front of Incinerator similar to the Tal’darim Mothership Thermal Lance. Dealing 10 damage and set the ground on fire. Dealing 150 damage over 5s. This ability dps stack with fire beam passive. Have 60s cooldown.
_ Anion Pulse-Crystals researches cost increase to 200 M&G. Now allows Mirage to attack 3 targets at the same time if they are within range.
_ Interceptor deal +5 vs air.
_ Repair drones can cast Fortification Barrier on Units if this was researched.
_ Fortification Barrier’s research cost increase back to 150 M&G.