The bloater in the high school on the last of us on grounded mode. When I entered the gym to fight it, my health was less than half full, so I had to start with that every time I died and restarted the fight. I hardly had any ammo either, so it was a constant cycle of sprinting around the gym and getting one punch in on one of the infected that chased me around until it died and dropped ammo, then I would have to use that small amount of ammo it gave me to pick away at the bloater, and keep running and punching the infected to get ammo.