Titans are... I guess they're like monsters, but they all used to be human. It's complicated. But they're giant, human monsters that eat people. Like, that's all the do, constantly, never stopping. I was trained in the military to exterminate them. Some of them can harden their skin, so it's like armor.

Thunder spears are what we use to crack the armor. They're jet propelled, and they have explosives packed in the tip. They bury in the cracks between the plates and then explode. It's the only way to get to their weak spot with the blades after.