It's a Forgeworld Variant called the SlaughterFiend Bloodpack (Apocalypse Reloaded) with the Blood Ride rule: "A squad of Khorne Berzerkers that starts its Shooting phase within 2" of a Slaughterfiend may, instead of shooting or running, clamber onto it, hanging on to the Daemon Enginer with chainaxes and hooks. The squad is moved the same distance as the slaugterfiends run move, remaining within 2" of the slaughterfiend. It's very handy, as back in 5th edition they ran 2D6 and Berzerkers could charge as if they had fleet once they disembarked from the special movement. Though if a Double 1 was rolled, a Berzerker went 'squish'
The game needs vehicles (and I'm glad by the dev statement that they are, or supposed to be in). Would be rather silly if suddenly all the forces left anything that resembles a vehicle behind, its not like they serve any purpose for the factions.
I read somewhere that khorne bezerkers would be able to ride predators into battle. not sure on how accurate that was.
