A complete guide to Prime Wars in Once Human: Mechanics, strats, and more

Prime Wars in Once Human are tower defense world boss battles that can have up to 40 players each. They unlock during Phase 2 of the Manibus Seasonal Scenario and feature three different bosses: Secret Servitor, Ravenous Hunter, and Shadow Hound. Players might be familiar with the latter two, as they are alternate versions of the first and fourth Monolith bosses, respectively.

Additionally, a fourth and final boss, Manibus, is introduced in Phase 5. You are required to defeat it multiple times to complete the Seasonal Goal.

This guide covers everything you need to know about Prime Wars in Once Human, including how to defeat the various bosses.

How to complete Prime Wars in Once Human

The Staroid Restrainer is the primary objective you must defend from the boss (Image via Starry Studio)

The basic strategy for setting up your tower defense during Prime Wars in Once Human is generally the same for each boss. Your first priority is to build structures around the Staroid Restrainer.

Start by placing marble or stone platforms and constructing walls around the Staroid Restrainers to protect them from enemy attacks. But avoid overbuilding, as this can not only worsen the lag — which Prime Wars are especially known for — but is also ineffective.

For example, some players spam Wooden Fences throughout the area, which is not only pointless as they are easily destroyed but can also cause one of the bosses to bug out and get stuck in the sky.

The bosses spawn from silver slimes on the ground, usually located a bit farther away from their Staroid Restrainers. Place platforms around these spawn points to slow down both the bosses and any spawned enemies from advancing toward the objective.

This will also increase your block damage, one of the key criteria for earning rating points in Prime Wars. Along with blocked damage, your ratings are also determined by your damage output and healing done. Depending on your rating — which differs for each boss — you can earn up to three tiers of loot crates, each offering lucrative rewards.

Lastly, place Gatling Cannons equipped with Biomass Missiles on platforms with a clear line of sight to the boss spawn locations. These missiles are essential for breaking the shields that bosses will acquire multiple times during their battle. These shields are immune to regular damage and must be broken before the bosses can take any damage to their HP.

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How to defeat Ravenous Hunter, Shadow Hound, and Secret Servitor in Once Human

Prime War bosses are prone to game-breaking bugs (Image via Starry Studio)

Battling the first three bosses is relatively straightforward. Start by breaking their shields with Biomass Missiles, which staggers them. Then, deal damage until they become immune and regenerate their shields. Repeat this process until they reach about 20% HP, at which point each boss transitions into its second phase:

Ravenous Hunter fires a missile into the sky that slowly descends. Everyone must attack the missile to detonate it mid-air before it hits the ground and kills everyone.
Shadow Hound jumps into the sky and lands with a massive explosion near the Staroid Restrainer, making it a DPS race where you need to kill it before it destroys the objective.
Secret Servitor splits into three separate after-images, which you must defeat one by one.

While Hard and Pro difficulties unlock in Phases 3 and 4, these encounters are essentially the same as in Easy mode but with higher-level bosses and enemies that deal more damage, requiring more missiles and ammunition to defeat. Other than that, the mechanics remain largely unchanged.

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How to defeat the Nightmare Prime War boss in Once Human

Manibus is the final Prime War boss in Once Human (Image via Starry Studio)

In Phase 5 of the PvE Seasonal Scenario, the final Prime War boss, Manibus, is introduced, but it’s only accessible in Nightmare difficulty. This colossal creature appears in the sky, featuring three tentacles, each protected by shields similar to those found on previous bosses. However, only Red Plasma Missiles can damage these shields, making Biomass Missiles useless for the main boss.

To defeat Manibus in Once Human, you must systematically break the shields on each tentacle and destroy the corresponding arms. Meanwhile, the previous three bosses — Secret Servitor, Shadow Hound, and Ravenous Hunter — will also spawn on the ground and target the Staroid Restrainer.

When defeated, these mini-bosses drop three Red Plasma Missiles and then respawn after a few minutes. This means you must repeatedly take down these mini-bosses while simultaneously focusing on destroying Manibus's tentacles, all to prevent them from destroying the Staroid Restrainer. Once you defeat the main boss, the battle ends, and the mini-bosses stop respawning.

All previous strategies are still applicable in the Nightmare Prime War, but the scale is much larger. Unlike earlier difficulties where you faced a single main boss, this battle includes multiple mini-bosses that spawn throughout the encounter, along with a separate main boss.

However, if you bring enough Red Plasma Missiles and assign separate groups to handle the mini-bosses with Biomass Missiles while the main group focuses on the main boss with Red Plasma Missiles, the fight becomes much more manageable.

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Edited by Dinesh Renthlei