I'd sacrifice an Imetron and Ikadron to get another Unidron. This way once the ML (I'm assuming it's there to ARO) goes down, you can still have a full Core link with a Spitfire. T-Drone probably won't see a lot of action, it's a niche unit and M-Drone is usually a better spotter for it... but it can also be completely unexpected and fun when it works.
It's also worth mentioning that, as a veteran who's often also a specialist, the Malignos is also a super good and highly versatile Classified Objective grabber.
I'm very disappointed in the Malignos, as the proliferation of models with chain-colts or nanopulsers makes it template food 75% of the time. Whenever I try to field a Malignos, the enemy has always zerged the mid-field with Libertos or Taighas or Muttawi'ahs or something else that forces it to eat a template wherever it goes. Still, I'm impressed with the strategy tips in this thread, and will definitely give it another chance now!
I haven't played OCF in ... over a year? ... so I can't speak to the current meta. But for what it's worth, back when did, I leveraged the Malignos FOs as often for objective-grabbing as I did for taking out enemy TR bots (have fun with those mods once your boy is a marker state inside 8"). I never regretted including them in my lists - and I always had at least one. Malignos--and any comparable unit in other factions (Crocs in PanO spring to mind)--are crazy reliable if you use them correctly.
Take to the rooftops or clear them from another angle. Double Malignos, one on each flank for example; opponent can't be everywhere, though massed warbands can come close to that. You can also used a forward-deploying bait, like Aida or Kendrat, to direct where Impetous units go. Preferably making them cross the sights of a Q-Drone or a sniper.
So, if you run the Dazer+Antipersonell mines Malignos, should you generally wait to reveal him, or if you get first round, should you reveal him in order to be able to deploy stuff before the opponent's round? Would you prioritze putting him in a large combat group, or could he do fine in a group with just a few orders available?
For the dazer, he's there as a roadblock, so I would put him on a smaller group. Reveal him to lay down a dazer and/or some mines, maybe drop into SF fire if you can, then leave him there until the opportunity to do something with him comes up. Maybe if you want to preserve orders you can lay a dazer and/or mine, then use an order to go back to marker state.
Has aynyone mentioned to be careful deploying the Dazer if the enemy has templates? If you do not position carefully, they can just shoot the dazer and clip your malginos without needed to discover it. Keep that in mind
I had some success with the monofilament Malignos today. It was 400 pts Tactical Window though, so I expected to face lots of heavy hitters. I might not have chosen the profile in other circumstances, perhaps, but in this one, it was great. The enemy had an insanely terrifying defensive link team with three Tankos with Missile Launchers, and two Domaru butai. But I snuck up on them and dropped a monofilament mine that could hit two of them, which basically pacified them for a whole game turn. Once they had dealt with that, I placed another one and shot at them, and the whole link elected to dodge. They did dodge the mine (though we mistakenly thought their Sixth Sense Lvl 2 took away the -3 PH mod, so one of them should've been hit), but I got two shots in and killed a Tanko, robbing them of their +3 BS bonus. Had I placed regular mines instead, it wouldn't have had nearly the same control effect - but for a link team of heavy infantry, a monofilament mine was simply something they absolutely couldn't ignore. I also like the combi rifle a lot. Those range bands on a TO Cammo guy are just so sweet.