Valhalla
Valhallans are simply people born on the incredibly fucking cold planet of Valhalla. Ergo.
As Imperial Guardsmen, they specialize in DYNAMIC ENTRY through ice and snow, often through the use of a curious drill-tank thing that has a quantity of flamers mounted on it. They have also been show rather good at holding the line. As if most Guard regiments didn't do that already. They just love wearing green armored greatcoats for some reason.