The invincible title where you get it when you regenerte 5 times after getting hurt by enemy in a rew.
I have done this many time and yet I can not unlock it this teday while playing infected i was shot and regenarted 5 times and still did not get title =(
I don't think you can get it playing infected.
It worked for my friend in infected, i even got to do this in kill confirm and still nothing
I unlocked it by accident playing on dropzone, you could try there see if that works.
got this using an assault juggy, got it first time.
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