In this chapter of the Gears Tactics guide, you will learn all about the enemy type attacking from a long distance - Sniper.
This is the first opponent that poses a very high threat to your soldiers from a great distance. His shots are very accurate and can inflict heavy damage. The biggest threat is the ability to pin your soldiers and track their positions. When a Sniper Drone does this, you can see it targeting your people with a laser sight. This is a very dangerous variation of the Overwatch mode, because if your soldier moves while tracking, they will receive massive damage. If two enemy snipers aim at the same soldier, that unit will surely die. This ability seems to ignore even the bonuses received from covers.
You need a mobile character to quickly defeat this enemy by inflicting a lot of damage in a short time. Take advantage of high obstacles such as walls, trucks, etc. to cut the Drone Sniper's field of vision. It is best to use fast characters - for example, a Scout can use their "Hide" ability to get close to the enemy unnoticed. Some of this class's abilities allow it to inflict additional damage while hiding, which only favors sniper hunting.
Vanguard can use "Intimidate" action to disrupt the Drone Sniper's ability. That unit can then approach and use a bayonet or allow the remaining squad members to easily eliminate the enemy. Throwing a grenade, using "Disabling Shoot" with a pistol or stun shot will also trigger "Interrupted" status and prevent the enemy from using that ability in the given turn. You can also simply try to eliminate the enemy with your own Sniper. If you feel that you aren't in a good position, it is better to retreat and create better conditions for a counterattack or a flanking maneuver.