The Speculo Killer has two different profiles armed with either a Combi Rifle or Boarding Shotgun. Offensive tools shared across both profiles are a pistol, Monofilament Close Combat Weapon, Smoke Grenades, Martial Arts 3. Impersonator Marker State grants them Surprise Attack and Surprise Shot making them even more deadly when they attack as a marker.
With ARM 1 and 0 BTS the Speculo is a glass cannon. The only real defensive tricks they have access to is Smoke Grenades allowing for a Special Dodge with their PH of 12 and an AutoMediKit.
Hunting the enemy Lieutenant, TAG, or other high value targets is the usual use of a Speculo Killer but sometimes they are better placed in the midfield to allow your specialists to take objectives unopposed. This is most useful in the Shasvastii sectorial army which has no other access to smoke.
Because it takes two full discovers to reveal the Speculo Killer, if your target is obvious, you can walk up to 16" taking discovers without any fear of enemy attacks including mines and perimeter weapons. This is an expensive prospect for the third order, but if it puts the enemy in Loss of Lieutenant or down a TAG it is probably worth it.
A Speculo Killer is a high priority target for the enemy making it a perfect bait unit. Coordinating with Hidden Deployment or Camo units you can draw LoF on enemy units trying to discover the Speculo and ideally bait them into an ARO they would rather avoid.
They have access to AutoMediKit on all profiles however meaning that players should take care to think of where the trooper will end their movement. Moving into then out of line-of-fire is best, or assuring that the model is behind a barrier so they will drop out of line-of-fire if knocked unconscious are best. This will allow you to use the AutoMediKit without provoking an enemy ARO. Also remember that multiple models can use a Coordinated order to all AutoMediKit at once forcing less ARO or allowing you to efficiently recover multiple troopers.
The Speculo Killer is like a high school gym teacher. They are scary, but it does not help you to be afraid of them.
Spotting a Speculo before they are deployed is extremely valuable. If the enemy is playing Generic Combined Army then there is a chance you will see one. If they are playing Shasvastii Sectorial Army your are almost guaranteed one if not two. Deploying your Lieutenant, TAG or other high value assets accordingly will help. A somewhat more high risk strategy is a "dummy Lieutenant." I you have multiple lieutenant options in your army you can place a non-Lieutenant in a supposedly safe position (prone on a roof top, in a building with no other models) to try and bait the Speculo to target them incorrectly. The danger is that your real Lt. will have to be somewhere a line trooper would normally be placed and could get killed for their efforts but it can work on some opponents.
Fireteams of 4+ and models with sixth sense are a natural enemy of the Speculo Killer. The deny the Surprise Shot and Surprise Attack modifiers that they need to kill their targets without reprisal.
The Speculo Killer succeeds in two ways: by killing a high cost/value target, or by costing a lot of orders to remove. You have less control over the former than the latter so let us focus on that first. Decide before hand how many orders you can afford to waste on the Speculo. That is to say "even if all of these orders fail, I can still do what I need to this turn." If that number is more than the number of orders needed to move vulnerable units away, then ignore the Speculo Killer. When you do try to clear a Speculo Killer the -6 from Impersonation level 2 means you will need high quality discover rolls. Try to get within 8" and/or use a link team member in a 5 strong link to make those rolls. Troopers with Biometric Visor are also ideal for this. If the plans fall apart or you fail all your discovers, place a few troops with LoF on the Speculo (ideally with the low WIP ones in Suppression Fire state) and drop mines along their likely approaches.
If you have a numbers advantage you can also Coordinated Order a group of troopers up to literally surround the Killer and force her to reveal or do nothing.
This profile has the Spawn Embryo rule so when unconscious, it still counts as a scoring unit for scenarios like Quadrant Control or Supremacy. You can bypass this by killing them out right with Shock, Viral, or Mono-filament, or by killing the unconscious models. Shasvastii sectorial players may focus extra attention on your sources of shock. Try to use that to your advantage.
Speculo Kilers are expensive and only available in Generic Combined Army and the Shasvasti sectorial army. They are usually a good investment in either but Shasvastii benefit more from them because of access to smoke. A Speculo is a high risk piece. You will almost always lose them, but if they kill the right targets, it really doesn't matter. consider them on forces where you have a high leadership Lieutenant, or lack infiltrators or other ways of effecting the enemy deployment zone.
The better you are at judging the biggest threat provided by the enemy force the better you will become with the Speculo. The basic impulse is to throw her headlong at the highest point cost enemy, but sometimes they are better served going after a lower cost model that is giving an essential benefit such as a MSV trooper, hacker, or doctor. If you can, with certainty, identify the enemy lieutenant and deploy close enough to take them out, obviously go for it. But the subtle use of the Speculo, say counter deploying against enemy midfield troops, can be more powerful.
A special note for the Shasvastii sectorial using two Speculos: you can combo your Speculo killers, placing one in a good position to enter the enemy deployment zone to force your enemy to deploy counter to it, then place the second one exploiting newly revealed weaknesses. You can also place the second Speculo to provide smoke cover for the first, allowing her a clear path deep into the enemy Deployment Zone.
Active Turn Role
When possible the Speculo wants to get into close combat with a single enemy, ideally from out of Line of Fire and when appearing from Impersonator state for the -6 Surprise Attack modifier. The boarding shotgun variant can also hit multiple enemies with a template, but Burst 2 can still fail you against multiple ARO. Like most aggressive pieces, the Speculo will do well to deplete the enemy order pool, but its unique combination of equipment and skills means it earns its keep best when killing hard targets.
Smoke Grenades are your best bet to dodge but the Speculo will often be targeted with template weapons. Try to end your active turn at least a few orders away from the enemy and in Impersonation state to make it as hard as possible to remove you.
When in Impersonation 1 state always wait to be discovered at least once before deciding to reveal yourself. The odds of discovery are low, and if the opponent fails they will have to try again next turn.