Morlocks are your cheap breakthrough infantry to go when you need to punch a hole into enemy defenses for a budget. With profiles ranging from a mere 6pts to 14pts, you are guaranteed to be trading positively most of the time when you kill an enemy troop in a firefight exchange.
The most relevant weapon on many of the Morlock profiles is the Chain Rifle, a direct template weapon that, while not the most damaging, can net you a good amount of kills, specially against tightly grouped light infantry. Also, being a direct template weapon, ignores target cover and BS penalties like those applied by camo, TO or suppression fire, thus making the Morlocks a very useful troop to engage highly protected targets. Is there an ODD trooper in suppression fire behind that corner? Don´t waste your time trying to outgun that -12 penalty to hit. Send a 6pts Morlock for a guaranteed hit on the offending enemy.
Morlocks are pretty good melee combatants with their CC 22 and Martial Arts lvl2 and also sport a wide range of close combat weapons for almost any situation. So be careful to choose the flavor that bests adjust to your game plan. If you expecting to find TAGs on the field, don´t leave your E/M weapons at home. And if you need to destroy some mission objectives, be sure to carry anti-materiel weapons.
One of the most offensive Morlock loadouts also carries a deceptively good Assault pistol for just 2 extra points. On a troop able to be fighting at mid to close range from turn 1, these Burst 4 handguns can put a hole in anything within 8". Their higher burst will also be more effective than normal pistols against targets beyond the Chain Rifle's range, although still not an ideal situation. They are ideal for removing ARO pieces if you can get close enough, clearing the way for your actual damage dealers.
Morlocks can provide a pretty good first defensive line for your army. Their chain rifles can exert zone control pressure on advancing units that will need to endure the sure hit or take a detour. The smoke grenades also provide a critical LOS denial to enemy ARO pieces that can not only protect the Morlock but also cover the advance of troops that need to get to optimal range or button pushers that need to activate consoles or other objectives with little protection.
Morlocks have a pretty decent PH attribute, so they can not only toss grenades but also dodge quite reliably thanks to their Kinematica skill. If their metachemistry roll gets them the +3 to PH they also become quite adept at lobbing grenades at longer ranges.
Morlocks have 2 attributes that are pretty deceiving compared to other warbands. They have a very decent BS11 that can do magic with the assault pistol profile, and have a very high WIP of 14 that not only can grant you a lot of objectives that do not require specialists, but also can prove useful in dealing with camo troops.
Don´t forget you can also Intuitive shot a camo marker with your Chain Rifle, and that shot uses the WIP attribute. So Morlocks provide a pretty good answer to those pesky hidden troops.
The metachemistry skill also grants you a lot of random tricks. Try not to forget important and useful defensive skills gotten from the roll, and use the movement skills aggressively to catch your opponnents off guard.
Last but not least: as any smoke lobber, Morlocks have excelent sinergy with Intruders and any other multispectral visor troop you might bring. A trooper with a visor can fire from inside the smoke cover applying a -6 BS to the face to face roll enemies being targetted. An Intruder using surprise shot from behind a smoke cover can apply a devastating -12 penalty to the opponents BS roll, which is probably one of the most reliable ways to reduce any opposition.
Multispectral visors are obviously the easiest way to deal with Morlocks, as they lose a fair amount of protection as soon as their smoke cover goes down. High armor troops on cover can also reliably overcome their DMG 13 weaponry range as long as they don't end up in close combat.
With total availability you can go wild with how many Morlocks you can bring. In scenarios where you have 3 midfield objectives for example is useful to have 1 morlock for each of them, so they can obscure the objective with smoke grenades alowing your specialists to close in to the objectives safely without fearing AROs.
Be mindful though as they are irregular so they do not provide a regular order to your pool and fielding too many of them can leave you short on orders you need for other important pieces in your army.
Ideally Morlocks should be deployed in your front line as they want to engage in close combat as soon as possible. They do not benefit from cover, so unless you are going second, don't worry too much with hugging those walls. Just be sure you are out of line of sight of the enemy for your first order activation.
If you are going second, use their chain rifles to block narrow avenues of attack or possible drop troop entrances.
Active Turn Role
The main purpose of the Morlocks on active turn is to open avenues of attack for the rest of your force, either by opening holes on the enemy's defence or by setting up smoke cover for your other troops, so they can take objectives or move without opposition.
Use them to dislodge opponents with heavy BS penalties working in their favour.
They can also serve as camo hunters if you lack any other tool in your army that is better suited to deal with them.
Not too reliable for ARO duty due to their lack of ranged options and access to cover, they can act as good zone denial pieces thanks to the great coverage of the chain rifle. Hide them behind corners to force enemies into chain rifle fire.
If the enemy doesn't have visors, their grenades can provide aditional cover for your troops in reactive turn if you manage to land a grenade that obscures their main offensive pieces. Be wary though as you might compromise your own defenses with this tactic too.