Helldivers 2's Halo: ODST crossover is also its first Legendary Warbond, focusing on stealth "for the first time" and adding 4 guns, 2 armor sets, a new armor passive, and cosmetics

Helldivers 2 x Halo ODST armor.

Helldivers 2's heavily teased Halo: ODST crossover has officially been announced, adding some Xbox flavor and the first-ever Legendary Warbond to the PlayStation-published co-op shooter.

A PlayStation blog post notes that, for Helldivers 2, ODST has been rebranded to the Obedient Democracy Support Troopers, "AKA The Helljumpers," which I sure don't remember from Halo 3.