The mastery challenge for the sticky bomb launcher on the shotgun in Doom Eternal says to destroy 25 Arachnatron turrets using sticky bombs. What exactly is that?
Arachnatrons are the big spider enemies that look like they have big brains on their bodies. They have a sort of scorpion tail that sticks out over their back with a turret on it. It’s their weak point. Shoot it with a sticky bomb to blow it off. Do this 25 times for the mastery.