Blue

An unusually large Crystalisk encountered in the Caustic Caverns, Blue is referenced by the ECHO recording found at the entrance to the caverns that Dahl security officer Elyse Booth had found, befriended, and been told to kill as part of the company's mining operations. Booth refused to kill her new friend and was executed. When the crystalisks retaliated against the humans, Blue killed overseer Harchek, apparently out of revenge for Booth's death.

Strategy
You will encounter Blue during the mission Safe and Sound, in which it guards Marcus'ssafe. The boss fight is fairly straightforward. Tactics in destroying crystalisks should be used against Blue as it is essentially a giant crystalisk. His 3 massive legs are his critical hit locations and are simple to shoot due to them being extremely large. Using melee attacks on his legs will take out a significant portion of his health quickly. Although Blue is massive in size, he can still be rendered immobile by Maya's phaselock action skill.

Should you take too long to kill Blue, he spawns several explosive Mini Crystalisks, and can regenerate the crystals on his legs.

Bugs

 * Standing underneath Blue when he is killed will cause the player to be trapped under his hulking mass as it comes crashing down. Once Blue falls and buries into the ground however, the player will be able to move out of his body.