Legendary Bloodbugs are the absolute worst because you can't really cheese them with geometry, and they will chase you forever, and they can be extremely difficult to hit outside of VATS. I'm level 20 with fantastic gear and completely wrecking everything up to this point. I just hit a legendary bloodbug that I am NOT underleveled for (no skull) that has killed me 5+ times. I am literally loading back to Sanctuary right now to grab fully modded out Power Armor and a Minigun. This is fucking ridiculous, I can two-shot named armored baddies but this bug is basically a God.