For the Legendary Cazador, you're in a dark cave, and all you care about is getting the Enclave Helmet.
Then, when you least expect it, you're in a tiny little room, and a giant tarantula wasp about the size of a train jumps out at about 50 miles per hour.
Then you get poisoned, and you die.
There's a Enclave Helmet in there? The LC was IMO the easiest "boss" in game... I went in that cave at lvl 18 with an assault carbine, ED-E and Veronica (Hunting Shotgun). The battle was over so quick I didn't even realize I had killed it untill I found the body,
OT: none of the legendary creatures were "hard," but the bloatfly was a nasty surprise...