A new expansion for Blackstone Fortress is coming out soon. It's called Ascension and with it will come some all-new foes for you to fight against. If you've been stopped by the Spindle Drones, then you'll definitely want to be on the lookout for the Guardian Drones, their bigger cousins, lurking around.
From the article:
Anyone who’s ventured into the Blackstone Fortress will know how deadly Spindle Drones can be, especially when their threat level rises! Today, we’re taking a look at their bigger brothers, the Guardian Drones.
Ascension, the new Blackstone Fortress expansion, sees the fortress itself awaken. Even more defensive systems are coming online – one of which is the Guardian Drones. When Spindle Drones aren’t enough to stop your explorers, the fortress unleashes these larger constructs.