The Riftbreaker

Drillgors are the big guys that proceed each base attack in the Crystal Caves biome. They look like a giant crab (six legs, 2 pincer arms and 2 scythe appendages coming out their shoulders), they have their own mini map icon during the attack so they should be easy to spot (Note: they’re almost always scannable with your bio scanner and they drop very high end loot, so sure to visit each location one was killed).

There’s usually 2 during a small attack and 3 during a big attack so you should get this relatively quickly during the campaign.

Note any time you start a drill will trigger an attack on your base as well (these are usually big attacks so be prepared with towers and walls and plenty of energy).