- Build a Boss parts are offensive upgrades you attach to your boss in the Edit Boss menu to survive waves.
- Buy order matters: start cheap with the Gun and Barb, then save cash for the Turret, Lance, or Mortar.
- Skills multiply part damage: Sharper Shots, Power Load, and Lucky Shot are top cash picks.
- Gems go to Scavenger for a +35% pickup rate, meaning more loot per wave.
- Never upgrade the boss too early — parts and skills give better value at the start.
How the Parts System Works
In Build a Boss, your boss is a customizable fighting machine. Between matches you open the Edit Boss menu, spend the cash you earned from clearing waves, and bolt new parts onto your chassis. Each part adds firepower in its own way — some fire bullets, others deal melee or splash damage — so your loadout defines how comfortably you clear each stage.
The core loop is simple: fight waves, earn cash and gems, buy parts and skills, then push into harder maps like Scraps and the Slag Run. Early on, your starting boss is fragile, so the first few purchases carry the most weight.
Video Highlights:
- Buy a weapon from the shop before your first boss fight
- Claim daily login rewards, favorite the game, and join the group for free crates and gems
- Recommended first skills: Power Load and Sharper Shots
- Save cash for the Lance or Mortar instead of upgrading the boss early
- Strafe constantly with WASD and shoot the arrows that mark enemy directions
Upgrading the boss itself raises difficulty for slightly better rewards. Skip it early — parts and skills deliver far more power per cash spent while you're still learning the wave patterns.
Parts Overview and Comparison
Every part slot you fill should push your damage output up. Below is a quick comparison of the parts you'll encounter most often and when each one earns its keep.
| Part | Damage Type | Best For | Value Rating |
|---|---|---|---|
| Gun | Ranged bullets | First purchase, tutorial fights | ★★★☆☆ |
| Barb | Melee spikes | Cheap filler slot, close-range maps | ★★★☆☆ |
| Turret | Auto-firing sustained shots | Mid-game all-rounder | ★★★★☆ |
| Lance | Heavy piercing hit | Boss-killer, save-up target | ★★★★★ |
| Mortar | Splash damage | Crowded waves, grouped enemies | ★★★★★ |
If you only have a few hundred cash, grab the Gun and a Barb so every slot does something. Once you're clearing maps like Scraps with 1,900+ cash banked, skip small buys entirely and save for the Lance or Mortar — both outscale everything cheaper.
Best Parts by Game Stage
Your shopping list changes as maps get harder. Here's how to allocate cash across three progression stages.
Early Game
- Gun: mandatory first weapon
- Barb: cheap extra slot
- Focus: surviving wave 3 on the first maps
Mid Game
- Turret: sustained auto damage
- Second weapon slot filled
- Focus: farming Scraps for steady cash
Late Game
- Lance: heavy single-target burst
- Mortar: splash for the Slag Run swarms
- Focus: full loadout plus gem skills
The Slag Run throws dense swarms at you, which is exactly what the Mortar's splash damage is built for. On more open maps where enemies stream in from one direction, the Lance's heavy hits clear priority targets faster.
Skills That Pair With Your Parts
Parts are only half the build — the Skill Map upgrades make them hit harder and pay you back more per run.
| Skill | Currency | Effect | Priority |
|---|---|---|---|
| Sharper Shots | Cash | Deals more damage to mobs | ★★★★★ |
| Power Load | Cash | Faster, stronger firing | ★★★★☆ |
| Lucky Shot | Cash | Bonus damage value per hit | ★★★★☆ |
| Scavenger | Gems | +35% pickup rate for more loot | ★★★★★ |
| Spotter | Gems | Zooms out, reveals enemy positions | ★★★★☆ |
Scavenger is the standout gem upgrade: a +35% pickup rate means more loot collected every single wave, which compounds into faster part purchases. Pick Spotter second if you keep getting ambushed from off-screen.
Step-by-Step Progression Route
Follow this route to go from a bare chassis to a fully loaded boss without wasting cash.
Claim Free Rewards
Log in daily, favorite the game, and join the group for free crates, diamonds, and gems before spending anything.
Buy Your Gun
Purchase a gun from the shop and place it on your boss, then clear the opening waves of the first map.
Invest in Cash Skills
Spend early cash on Power Load and Sharper Shots so your starter weapon carries you through Scraps.
Add Scavenger With Gems
Use gems on Scavenger for +35% pickup rate, boosting loot income on every subsequent run.
Save for the Lance or Mortar
Bank cash instead of upgrading the boss, then buy the Lance or Mortar to push into the Slag Run.
On higher waves the enemy bullets get thick. Keep moving with WASD, aim at the on-screen arrows showing enemy directions, and grab the Immunity pickup when it appears — it makes you invulnerable for about five seconds.
Farming Goals Checklist
Track your build progress with these milestones.
Build Milestones:
- Buy first Gun and Barb from the shop
- Unlock Power Load and Sharper Shots skills
- Clear the Scraps map and bank 1,900+ cash
- Purchase Scavenger with gems
- Own the Lance or Mortar and clear the Slag Run
FAQ
Q: Should I upgrade my boss or buy parts first?
Buy parts first. Upgrading the boss early is generally not worth the cash — parts like the Turret and weapon skills such as Sharper Shots give much better value while you're still building your loadout in Build a Boss.
Q: What is the best part to save up for?
The Lance and the Mortar are the top save-up targets. The Lance delivers heavy single-target damage, while the Mortar's splash damage excels against the crowded waves on maps like the Slag Run.
Q: How do I get more gems?
Log in every day for daily rewards, favorite the game, and join the group — each of these grants free gems or crates. Scavenger then increases your pickup rate by 35%, compounding your loot income.
Q: Why do I keep dying on later waves?
Standing still is the main cause. Enemy bullets track your position, so strafe constantly with WASD, shoot the arrows that indicate enemy directions, and grab the Immunity pickup for roughly five seconds of invulnerability.