Constructors from borderlands 2. (Pardon my language in this) These FUCKERS ARE TOUGH AF. I hate them, they have so much health, so much damage resistance, and their attacks deal massive damage. Don't get me started on how often they come up, after you meet the first one you'll encounter very often. They spawn in more enemies (hence the name), they release a powerful shock wave if you get too close, release a volley of missiles if you get too far, and both fuck you up completely. I'm talking about only the normal variation. The badass variation hits harder, takes more hits, and spawns a turret as combat starts. The super badass variation is three times harder then the badass variation and has super missiles. Their weak spot is the eye, but it's so small compared to the rest of it, and this is just the normal diffilculty.
Now allow me talk about a unique named enemy called "saturn". Hits like a tank with a top speed of 200 mph and nitro boosts before it hits, and takes hits like said tank on armor boosting steroids. Only encounter it once, but damn.
These are pretty much tougher than the final boss.