Boardwalk Empire has it's share of rather brutal death scenes (after all, a dude being shot in the head never quite loses its effectiveness), but that's not what this is from.
This is from
Fullmetal Alchemist: Brotherhood. Not to give too much away in case some folks reading this don't want plot details spoiled, but
a dude uses magical fire to roast a woman alive until she literally turns to dust. Oh, and she's screaming in agony the entire time.
Seriously, if you want to watch it, go right ahead. Probably won't be as hard to watch for you as it was for me, but still...
Really the entire scene it happens in is pretty hard for me to watch. Maybe I'm just a total pansy, I dunno.