The Blood Symphony Add-on for Bulletstorm has 5 achievements worth 125 gamerscore.
On Mean Street, kill all the snipers on the rooftop before the DNA bomb explodes
On Monorail Factory, kill all enemies whilst riding the lift
In the Rock Quarry map kill an enemy using a Mine Cart, Oven, Fan, Smasher and Lava Cart in one wave
Kill every enemy in a wave using only the Teleportation in the Ulysses map
Kill an enemy by thumping them into a helicopter in the Mini City map