Since Killzone: Shadow Fall will take place a few decades after Killzone 3, players won't fight the same Helghast opposition.
The Black Hand consists of a faction of radicals and zealots from the Helghan Sector. Bitter about [spoilers] the destruction of Helghan from Killzone 3, the Black Hand army will seek revenge through declaring war. Using their guerilla tactics, the Black Hand specialize in violence and sabotage. The rebel army will rely on surplus military equipment and makeshift weapons to hopefully bring down the government of New Helghan.
Guerrilla Games continues to reveal more information about Killzone: Shadow Fall as its November 15th release date approaches. While Killzone fans might still prefer information about the newly revealed multiplayer, these new details on the Black Hand will at least inform fans of the enemy they will soon face.
Killzone: Shadow Fall will release alongside the PlayStation 4 November 15th in North America and the 29th in Europe.
Source: Killzone.com