Hellbringers appear as trainable units in Halo Wars, operating in teams of two. Hellbringers can benefit from up to three unique upgrades. The first upgrade, Flash Bang, costs 200 resources and unlocks the Hellbringers' special ability, which stuns enemy infantry with flashbang grenades launched from their M301 40mm Grenade Launchers. The second upgrade, Napalm Adherent, costs 400 resources and allows the flames to stick to targets after the initial attack, causing continuous damage. The third and final upgrade is Oxide Tank, which costs 700 resources and provides the Hellbringers with a higher temperature flame, distinguished by a blue color, that deals increased damage to all organic targets.
Hellbringers are the UNSC's most effective anti-infantry unit, not only against standard units, but also against the Covenant's unique leader units, such as Honor Guard Elites and Brutes. This also includes the Covenant Leaders themselves. Their upgrades allow them to stun enemy infantry and safely make short work of them. However, they perform poorly against armored vehicles, and are totally incapable of attacking air units. They need to get close to targets to engage them, and are very vulnerable to long range units like Kig-Yar snipers. Researching the Adrenaline upgrade from the Field armory can increase the Hellbringer's usefulness by letting them get into range more quickly.
Garrisoned Hellbringers in sniper towers are incapable of attacking at all.
A good strategy is to train Hellbringers en masse and then transport them to the front line via Pelicans. This helps cut their casualties when traveling, as they cannot defend themselves from long range. As a defensive tactic, players can lock the base and train multiple Hellbringers. If the enemy attacks with vehicles or aerial units, the Hellbringers cannot be harmed until released from the base. A good offensive strategy is to group Hellbringers together with RPG upgraded Marines or ODSTs to protect them from ranged units. Don't send Hellbringers into battle against the Flood without allies. They become infected more quickly than Marines and, when infected, become Infected Flamethrowers. These Flood units can be exceedingly dangerous to infantry, and like rebel snipers, can take down a Spartan in seconds.
During Skirmish battles against Covenant teams led by the Arbiter or Brute Chieftain, it can be helpful to train large groups of Hellbringers. They can take down the Arbiter or the Brute Chieftain before they can cause much damage to your base or army, as long as the leader does not have many allies present.