Just Lucky I'm Alive/Lonesome Road

Just Lucky I'm Alive is a perk in the Fallout: New Vegas add-on Lonesome Road.

Effects
You've had lots of close calls. Whenever you finish a fight with less than 25% health, your Luck increases by +4 for 3 minutes. You are also immune to critical hits, and your own critical hits inflict +50% damage. The immunity to critical hits and the critical hit bonus damage are permanent and apply regardless of health percentage; only the luck bonus is limited to 3 minutes. Once you acquire the perk, the bonuses apply regardless of karma.