Borderlands 2

[Ryuho Tsugu]

Try it single player some time. Enemy health bars reset when you die, so you have to do it all from full hp without dying.

That reminds me of the time I tried to solo Dexiduous—got it down to 5% or so and ran out of ammo trying to hit those crit spots, then got killed through the wall of the lodge buying more ammo.

I was successful the second time, but damn.