Serum and binding: how to grow your horde fast
Updated September 25, 2026. Figures come from the live game.
The short answer
Bind at the Binding Pit: 6 serum and 20 biomass per batch, one batch at a time. An S grade in Serum Shot binds 5 zombies in 1 minute instead of 3 in 3 minutes. Serum is the limit, so upgrade the Serum Lab and research Distill; upgrade the Pit for bigger, faster batches.
What a batch costs and gives
| Serum Shot grade | Zombies | Bind time |
|---|---|---|
| S (900+) | 5 | 1 minute |
| A (750+) | 4 | 2 minutes |
| B (550+) | 3 | 3 minutes |
| C (350+) | 3 | 3 minutes |
Every batch costs 6 serum and 20 biomass (3 serum while you're rallying after a lost defense, and 30 % less with a Serum Lab on the Serum Reserve path). A level-3 Binding Pit adds one zombie to each batch, a level-5 Pit another, and each Pit level above 1 binds 8 % faster. Only one batch binds at a time.
What the Pit unlocks
The Binding Pit teaches your horde one thing at a time. Building it lets you bind Shamblers; each upgrade brings a new strain or a serum trait, with a short card that explains what it's for in a raid. Squads you already have keep fighting whatever the Pit's level.
| Binding Pit level | New strain | New trait |
|---|---|---|
| 1 | Shamblers: steady all-rounders | — |
| 2 | Runners: fast raiders, fragile | Climbing: barricades hold half as long |
| 3 | Brutes: gate-breakers, slow | Armor: +30 % health |
| 4 | — | Speed: +25 % speed |
| 5 | — | Spore cloud: stronger spore bursts (2 serum each) |
A raid carries two traits. Climbing pays off against villages that lean on barricades, Armor against towers, Speed on long marches, and Spore cloud in long fights at well-guarded gates.
Horde cap
| Binding research | Horde cap | Hunts unlocked |
|---|---|---|
| None | 60 | — |
| Level 1 | 72 | Shamblers (tier 1) |
| Level 2 | 84 | Runners (tier 2) |
| Level 3 | 96 | Brutes (tier 3) |
Getting more serum
- Upgrade the Serum Lab: each level multiplies its 10 serum an hour by 1.35.
- Research Distill: serum × 1.25, × 1.5 and × 2 at levels 1, 2 and 3.
- Pick Distillery at lab level 3 for another +25 %.
- Claim the daily reward: 3 serum × your streak day, up to 21.
- Play the Serum Shot, Serum Sort and Pipeworks paid runs in the Training Yard; all three pay some serum.
Bound zombies form squads of up to six in the Binding Pit's pen.
Questions players ask
How do I get more zombies in Voxhorde?
Bind them at the Binding Pit: 6 serum and 20 biomass buys 3 to 5 zombies. You can also hunt wild hordes, beat a wild horde at your gate to bind its survivors, or buy a Bound Pack for 20 gold.
What is the horde cap?
60 zombies at first, rising to 72, 84 and 96 with Binding research, plus 2 per Binding Pit level on the Brood Pens path and 12 per level of every Residence you build (no ceiling).
Do I need a Binding Pit to bind zombies?
Yes. Binding and mutating happen at the Binding Pit (40 scrap, 30 timber, 6 minutes, one per village). The Serum Lab brews the serum a batch costs and runs research.
Why am I always out of serum?
Serum is the game's pacing resource: one level-1 lab makes 10 an hour and binding, research, spores and hunts all spend it. Upgrade the lab, research Distill and pick Distillery.