You'll face the Unstable Scout mini-boss during the quest The Recluse of the Abyss. On this page of the Steelrising guide you will learn how to defeat this boss.
Despite a different name, the Unstable Scout is simply a more powerful Miner Automat (more about it on the Labourers page). This means he uses a drill he can swing widely. He can also switch it to an automatic mode and hold it in front of him. He can also spin a pickaxe which is usually located behind his back.
This boss will be extremely easy if you keep your distance, which isn't hard given how slow he is. Simply freeze him and attack when he's immobilized. Remember to stick to his back during combat.