The Haiduk brings a Multi Sniper Rifle which can be upgraded to a Smart Multi Sniper Rifle to give it the Guided Trait. It also has Sapper which grants it cover and Minimetism.
This gives the Haiduk the role of an ARO piece, but it is worth noting that it will not survive long against a superior shooter. The Haiduk is best used on a long LoF corridor secondary to the battle. Along the table edge or in front of several impetuous troopers when going second is ideal. If you paid the extra points for the Smart MSR it can still contribute to the rest of the battle from a limited LoF position.
Also remember that the Haiduk can leave it's foxhole and re-enter one as a short skill to allow it to redeploy or move to take out a target of opportunity or destroy an objective. Many opponents forget this.
with Sapper the Haiduk can be in cover anywhere. It's MSR should placed where foes must engage it from long range, or where it will take several orders to get a MSV trooper to shoot at it.
Remember that in addition to Cover and Minimitism, you also have Courage while in the foxhole. You can still opt to ignore this and go prone (leaving the foxhole) to gain total cover and sometimes this is the correct choice.
This profile has the Spawn Embryo rule. When the unit is unconscious, it still counts as a scoring unit for scenarios like Quadrant Control or Supremacy. Armies with large numbers of Shasvastii might consider taking out enemy units with Shock, Viral, or Monofilament as a higher priority to exploit this rule.
Failing a Guts will let you abandon your foxhole but go prone (assuming doing so gets you total cover). This is sometimes a good option. Because of the way Foxhole works, you can also place the model facing in any direction. On a roof top with a parapet this means you can:
A: drop behind the ledge to be out of LoF B: turn to face behind you so no AD trooper sneaks up on you.
The Haiduk want's an unfair fight. It can't shoot it out with an enemy MSV sniper for long, and even weight of fire will take it out with a linked HMG. Just be certain that you are not:
A: Walking into a Hidden Deployment trap B: misunderstanding how many penalties you will take (base of -6 and +/- range)
Also note that this guy loves to pick off Impetuous troopers and AD so don't give her the chance.
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 players may focus extra attention on your sources of shock. Try to use that to your advantage.
Haiduks are the best sniper option in Shasvastii and a fine choice for indirect fire as well. At their very low point cost they are a good option to add if you find your list near completion but needing one more good long ranged weapon, or if you have left over SWC.
As discussed above, consider areas where you will control part of the board but not be too vulnerable to a high powered enemy model. If you are worried about AD, have him watch a table edge. If your opponent leaves several members of a link team exposed and you can be in a position to only see them, consider it as an option.
With SEF especially and Combined Army in general, it is good to consider how much your deployment would cost your opponent to remove "at minimum" if it is 3-4 orders, then you are in a good place.
Active Turn Role
The haiduk provides a Smart MSR for indirect fire in active turn. If the opponent has foolishly left something in LoF of it, the Haiduk will be happy to remove them, but beware of using it to try and take out a TAG or HI unless the range is stacked in your favor.
The Haiduk is a fine defensive ARO but cannot out shoot a link team, close foe, or superior sniper. Try to use it on long LoF areas such as table edges or to place it in an area with good LoF that is normally lacking in cover.
Also consider guarding it with a Noctifer Missile launcher or other Hidden ARO so that an opponent trying to take it out faces an ugly surprise.