Harakoni Warhawks
Take the Elysian Drop Troops, now add 75% more manly, now replace their normal lasguns with hellguns and their flak jackets with carapace armor, and now make them all STORMTROOPERS and you have the Harakoni Warhawks, one of the most elite guard drop units in the galaxy.
All Warhawks hail from the Hive World of Harakon, where their massive Hive Worlds have spires reaching into the upper atmosphere. In order to hunt on their homeworld they use grav-gliders to hunt in the valleys below. Because of how they hunt, this makes them excellent at high altitude jumps as well as judging air currents on the way down. The Harakonis are very distinctive with their uniforms and many a guardsmen can tell if a guardsman hails from harakon from their distinctive dialect of Low-Gothic. Many Imperial Commanders owe thanks to Harakonis attached to their regiments.
Unlike Elysians, Harakonis make full use of heavy weapons teams and Special weapon squads which allows them to carve a path pretty easily.
GW doesn't have many encounters with them fighting much in the 41st millenia, (considering they're stormtroopers, it kind of explains why).
Basically when you absolutely, positively, need to GET SHIT DONE and require the kind of force that would last longer in a fight longer than elysians would on their own, the Warhawks will not dissapoint.