long post warning. TL;DR, Terrans take the cake here! I did a post on tower diversity in coop mode and thought it’d be fun to go through the these units as well
The scope of this thread will be units that have the “Detector” tag in its display area (to the left of the unit/building portrait). Also, actual units. As opposed to buildings that sometimes also get lumped in as “units”. As contrast, excluded will be buildings that typically have the “structure” attribute/type tag in its display area. However, I did another topic on tower diversity, so you use the link below to find out more about those…
========== Terran COs
OVERALL: Like with the tower diversity topic, our home team of Terran seems to take the mantle here!
----- Raynor
0, zip, zilch, nadda, goose egg.
In fact, Raynor is the only CO who does NOT have a detector unit! It’s quite unconventional, but he has Missile Turrets for detection at home base, and remote areas that aren’t quite the hot spots. They only do AA, but they at least do that well enough, and only eat up a 2x2 footprint. Contrast that to his bunkers which come with Shrike Turrets, but they’re quite weak, the structure takes up a 3x3 grid, and you’ll really want infantry in there to get more DPS/options (which takes up supply and additional resources)
His OC cover the rest of his detection needs. It may not be sustained detection, but your ally should be able to help out with that part. And it can be cast anywhere, so at least you won’t need to wait while they move into position. If I didn’t know better, I’d say they did this on purpose to steer new players towards making OCs in an attempt to discover MULES. If you’re playing his P1 then that’s more energy for com scan at least.
----- Swann
Science Vessel — 100/200/2 | 100/300/2 with P2/Grease Monkey
The only CO with SV! It isn’t the only detector unit with spells/abilities, but here, these are much unique as well!..
-Repair. Helps keep your units in the game longer. Your allies who have mech units will also appreciate this. Especially Protoss ones who cannot repair their own units! The oddball Zerg COs who also incorporate mechanical hardware into their armies can regen hp on their own, but that’s slow. They can send a worker for repairs, but that can get clumsy, and requires one to divert APM
-Irradiate is at least a way for them to do some damage to bio units, and defend themselves from such. Because there’s no friendly fire in Coop, you can slap this on your own bio units, or those of your allies, and they’ll be invincible to it, while doing damage!
-Defensive Matrix and is hardly unique, but it helps squishier units like his Goliaths from dying too quickly.
This is amongst the pricier in detector units (especially on his P2). However, Swann does have gas drones to help offset the gas costs.
----- Nova
Nova — with 75/75 upgrade. And up to 450 minerals to respawn instantly
Raven Type-II — 100/200/2
Nova is a beast of a detector unit! She’s got a full array of combat abilities, her ability upgrade to turn her into a detector also includes “Sensor Tower sight”. She has a certain vision, but that Sensor Tower extends beyond that into fog of vision, enabling her and her ally to see “blips” for enemy units or buildings. If she dies, she has the option to instantly respawn, which kind of eliminates the need for other sources of detection. That said…
Her Ravens can legitimately get overlooked because of Nova’s high utility. However, they’re on par with the spells offered by Swann’s SV. Here, dropping Rail Gun Turrets, Seeker Missiles, and bio-mech repair drone. The latter is Nova’s only way of healing bio only units (short of her mastery, which isn’t available to her allies ofc.). Last but not least, even though her Ravens are at standard costs (contrast that to her other combat units that are both elite in stats, and priced accordingly), her Raven production is still subject to the charge production system, so that can serve as a bottleneck (save for her P1/Soldier of Fortune and having Starports be the first production building done. Or Chrono abilities from Protoss allies).
----- HH
Theia Raven — 100/200/2 | 130/260/2 with P1/Chaotic Power Couple | 1001/60/2 with P2/Wing Commanders
Very similar deal with Nova and her Ravens above… they cost the same, includes the “sensor tower sight” thing, has a bunch of nifty abilities, are deployed directly to the rally point, and also restricted on charges for production. In “Silent mode” (more sight, but can’t move), it actually cloaks itself. A small but notable difference from all other detectors that have their own version of “silent mode”. As something unique to HH via the lv15/Significant Others talent, it contributes to the attack speed of Mira Han’s units, while her units contributes more hp to units like here.
However, it has no abilities that do (direct) damage. Another nice thing that sets it apart from nearly all the other detectors is Tac Jump.
----- Tychus
The Fixers… Vega, Nikara, and Nux | 500/100/10 + one upgrade that enables detection in all 3 of them.
Tychus plays like a MOBA character, so the dynamics here already differ. You cannot have multiple copies of any of them, so they will truly and literally be unique. They all have the “Heroic” tag. Another difference is since Tychus is also limited in the number of outlaws he can recruit, each hero unit has to be able to do about as much as multiple units of the same type would be able to (e.g., Nikara is easily the equivalent to several of Raynor’s Medics). They’re more fragile than “The Muscle” and even “The Guns”, but they still have far more hp than your typical, normal unit detector. Last but not least, unlike Nova and Dehaka, these can be revived quicker (bt of 25), but cost minerals (250).
They also cost 10 supply each, but during the course of normal game play, this is never an issue as you’ll be fine even with all 5 Outlaws available and full saturation of workers. For Mutations that muck with supply count, that’s a whole other thing.
Auto-Turrets are decent, but they’re more so for stopping nuking ghosts, and other unusual circumstances. (If turrets are play, they’re going to be coming from Sirius)
----- Mengsk
Imperial Witness (aka “blimp”) — 100/100/2
Another unique detector unit! It looks nothing like the typical Terran arsenal (in the campaign, we got Ravens Science Vessels. Nova and Tychus’ Fixers are templates from standard units), and its blimp appearance is rather delightful if nothing else. Arcturus wasn’t a nice guy in the campaign, nor in this theoretical/non-canon timeline, but in eerie ways listening to his voice and the Dominion propaganda has its soothing qualities. Works better if you’ve been listening to certain Coop mode’s NPCs too much (most notably, General Davis :\ ).
At 350 hp, it’s fairly hardy, but it does move much rather slowly, and has no options for speed upgrade (although ironically enough, another Imperial Witness going into Patriot mode will give it a movement boost). Most flying detectors have an “observer/surveillance mode” where they lose mobility, but gain 1.5x the sight. Here is no exception, but this also adds Patriot mode which consists indoctrinating LaTr (Laborers/Troopers), and giving all units movement and attack bonuses! Like a (Karax) Energizer field-of-effect!
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==========Zerg COs
OVERALL: A lot of Overseers (Os), so very little variety here. Still, 1 of them is radically different, and there are some CO specific things that set them apart…
----- Kerrigan
Overseer — 50/50/0. +100/0/0 if you count the cost of the Overlord itself
Kerrigan players will typically just pop Omega Worms onto the battlefield for detection, so save for her P1 or pre-lv8 talent unlock, you’ll likely never see these actually getting used.
----- Zagara
Overseer — 50/50/0. +100/0/0 if you count the cost of the Overlord itself
Zagara does have the quickest larvae production, and her Queens produce twice as many with their spawn larvae ability (for the few people who do use that, as opposed to making more Hatcheries 
). Bile Launchers can be a tool to deal with cloaked and burrowed units without detections (although like with her Queens, damned if I see anybody really make them).
----- Abathur
Overseer — 50/50/0. +100/0/0 if you count the cost of the Overlord itself
Abathur has better chance of using his Toxic Nests to hit ground units without having an actual detector, so there’s always that.
----- Stukov
Overseer — 50/50/0. +100/0/0 if you count the cost of the Overlord itself
One of the few things from Stukov’s tool belt that’s not “infested” (since it was already Zerg, as opposed to being twisted there). While it requires T2 level to be built (just like the Os), it’s at the Infested Factory level as opposed to Lair, so it follows more of the Terran tech tree (even if the difference may be miniscule). It also builds differently since his Infested SCVs and Overlords work on charges like Nova and HH (albeit with a much lower cd), and both share that queue.
Brood Queen — 100/100/2
Ocular Symbiote can make any unit now include Detector tag! Also includes a +5 sight for the typical 3 minute duration. Queens don’t get a lot of love, and even when they do, Fungal and “Zerg Yamato” tend to hog the spotlight. However, I’m told Ocular Symbiote has been excellent against certain Mutations.
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FWIW, Stukov can uproot his Infested Missile Turrets just like his Infested Bunkers to relocate (if there’s creep at the destination), so the added mobility helps there.
----- Dehaka
Dehaka — needs in-game lv5 plus attribute pt put into Keen Senses
Dehaka is figuratively and literally a beast at detection! Being a prime combat unit means he can play judge, jury, and executioner all at once! Like Nova, he can be quick-revived to get his detection abilities (not to mention his combat prowess) back into the action quickly. He has to level up in-game to unlock his ability to detect, unlock abilities, and really up his total hp, which is roughly on par with how other COs have to spend resources, time, and APM to climb the tech tree to enable building of their detector units.
Leveling up, he doesn’t gain the ability to add detection to his repertoire until CO lv5/Primal Insight, so Primal Wurms and Greater Primal Wurms will be needed (which is made worse pre-lv3 since none of them can Deep Tunnel until then)
----- Stetmann
Mechanical Overseer — 50/50/0. +100/0/0 if you count the cost of the Mechanical Overlord itself
If you thought Stukov was an oddball here with his Infested Terran, Stetmann has mechanical versions of Zerg. They can be repaired, and have the Mechanical tag but not the Biological tag. Similar to non-P1 Kerrigan and her Omega Worms, if you’re non-P1 Stetmann (or pre-lv5/Super Gary), people typically just exclusively use Super Gary for detection.
Super Gary — 300/450 upgrade from (regular) Gary
The caveat is the same as Kerrigan… if he dies, you’ll need to wait a minute for him to revive. The differences are: He comes with all of the quirks of Stetmann’s mechanical Zerg-play… Stetalites, Gary’s abilities that tie heavily into them, and all of that infrastructure supporting and boosting his own units, and those of his ally’s.
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========== Protoss COs
OVERALL: Akin to Zerg race above, a lot of Observers (Obs) here as well, but with not 1, but two exceptions. A bit different is there appears to be some more CO specific things that set them apart even though many of them are “just Obs”…
----- Artanis
Observer — 25/75/1
Here, Artanis has a few extra things to set these Obs apart… 1) they can get warped directly into a power field, 2) the production building can do both: have multiple charges, and do that direct warp in thing, and 3) with mastery points, have the “Warp in Haste” bonus applied to them
----- Vorazun
Oracle — 100/75/3
One of the Protoss detector units that isn’t an Obs!
Observers are all permanently cloaked, but these can be upgraded to do just that. Even though you can cloak these, their higher targeting priority over Obs has earned them some hate, since they tend to be shot down very aggressively/quickly. Having an AG attack that needs to be toggled on and off, constantly using energy, doesn’t seem to help.
Speaking of which, she has several talents that boost cloaked units. Also applies to Observers and Havocs (even if they won’t enjoy the benefits as much).
Since Vorazun cannot build a Robotics Facility, this one got lumped into the Star Gate building, which should facilitate getting those units up and running as well.
----- Karax
Observer — 25/75/1
Interesting to note that even from the get-go, Karax’ Obs were never slapped with the “unit tax”. Yet, they’re still considered “combat units” for the purposes of using F2. Later on when his lv1 talent was reworked to give his units +50% hp over the base standard unit type, they were still excluded from this. That was nice since that kept them cheaper to make. And if I done my math correctly, having the boost in hp and shields from both his lv1 talent and full 30pts of mastery into this would cause its vitals to go from 20hp and 40 shield, to a “whopping” 39hp and 52shield. I guess what little boost helps when you started off that low, but not a huge deal either. However, for his P2/Templar Apparent, it does mean this is the “worst of both worlds”… it doesn’t get the P2 discount, nor does it have the higher hp and shields.
This is probably one unit detector that you could really get away with not making, very few of, or very later on. Karax’ Pylons and Photon Cannons come in instantly, so they’re quick to set up, even on the field. Ofc., this isn’t an option for his P2. For stray cloaked/burrowed units, you can just zap them with Orbital Strike or Solar Lance (especially with his P3/ Solarite Celestial). When dealing with waves, you can still stand to get by with just those (in addition now utilizing Purifier Beam to better effect)
----- Alarak
Havoc — 50/100/1
–The other Protoss unit detector that’s NOT an Obs!
–The main thing that makes this unit unique is that it’s the only non-heroic, ground detector unit in the game, that can be created like regular units (unlike heroic units who are automatically available after a cool up time, and are only 1-of-a-kind)!
–Alarak has twisted the standard Protoss units to other uses (Colossus to Wraithwalker, does high single target DPS. Immortal to Vanguard, does splash damage). Here, a Sentry/Energizer/Conservator type unit still has an array of support abilities, but is now a detector
–The Observers are all permanently cloaked, but these can be upgraded to do just that.
–They’re different enough already, but are also 25 more mins and gas in cost
Justified, as they certainly do much more than just “detect”
----- Fenix
Fenix Arbiter suit
Observer — 20/60/1 | 10/30/1 with P2/Network Administrator
Yet another Obs, but his can be built much sooner, on account of Fenix not having to follow the tech tree. Also, his Robotics Facility costing 50% less mins, and no gas vs. the baseline cost further boosts this!
----- Zeratul
Xel’naga Watcher (XN Watcher, or still “Obs”) — 25/75/0
Yet another Obs, but with a different name. These have the same resource cost as base Obs, but they cost zero supply! So you can make these things and easily cover large portions of the map! However, it’s worth noting that this is rather a necessity, as unlike other Protoss COs, Zeratul is capped at 100 supply. Unlike other heroes like Nova, Super Gary, and Dehaka, and Fenix (Arbiter), Zeratul himself ain’t no detector.
Another big feature is these get free level upgrades and ability upgrades through Artifact Fragments! However, the latter requires his version of the Robotics Bay (Constructs Bay) to be built for those to be enabled. Last but not least is his version of the Robotics facility, the Constructs Facility (and all his other buildings really) do not use power fields, so they’re not hampered by that limitation
). But yeah, that’s something that I definitely was on the lookout for earlier on, as sometimes rushing to a detector isn’t always the most ideal thing to do. Especially early game (although sometimes, it is unavoidable).
, and this topic would not help.