How does the Diablo 4 mercenaries system work? Vessel of Hatred adds mercenaries as a new mechanic, giving you allies that can be called into battle or set as your main companion. They can be unlocked during the main quest in Vessel of Hatred, with each mercenary having unique skills and their own backstory. Diablo 4's expansion adds a bunch of new mechanics and content, from raising the Diablo 4 level cap to changing how difficulty settings work in Diablo 4. We're also getting mercenaries to aid us in battle, though they will need some convincing first through the rapport system. Continue reading Diablo 4 mercenaries explained MORE FROM PCGAMESN: Best RPGs, Diablo 4 review, Diablo 4 classes