This guide contains campaign spoilers through level 5.8 and mentions the developer and endless-game unlocks that follow the final storyline boss.
Fast answer
The answer before the background
The five storyline bosses are Broot on 1.8, Stakey on 2.8, Constructor on 3.8, Mobchain on 4.8 and Metaphor on 5.8. On normal campaign maps, they are tied to the late waves of those final stage levels. On custom maps, bosses normally begin no earlier than wave 40 and then follow the map’s boss configuration, unless a boss tile changes the schedule. Build for single-target damage, keep towers spread away from the path, and read each boss’s special rule before spending abilities. Boss victories advance campaign progression and produce normal game rewards, but no reliable source confirms a unique fixed drop for each named boss.
Quick reference
All five campaign encounters
The campaign introduces one main boss at the end of each major stage. The level and wave shown below are the first documented appearance; later versions or special maps can alter practical timing. In update 1.9.0, the developer increased boss health and slowed bosses, so a pre-1.9 guide may be misleading.
| Boss | First appearance | Main threat | Reliable counter plan |
|---|---|---|---|
| Broot | 1.8 | Rage below 25% health; heals from damage during rage | Use Sniper or Minigun and finish the last quarter quickly. |
| Stakey | 2.8, wave 46 | Armored head, damaging body and tail, increasing speed as it loses segments | Use Cannon, Tesla, Flamethrower or other area damage on the body; use strong single-target damage on the head. |
| Constructor | 3.8, wave 50 | Becomes invulnerable while repeatedly spawning enemies | Prioritize rapid single-target damage; Sniper is dependable and Minigun is strong on short maps. |
| Mobchain | 4.8, wave 50 | Head is invulnerable until body parts die; phase-two parts have displayed weaknesses | Diversify tower damage types and avoid relying on Freezing or Blast. |
| Metaphor | 5.8, wave 100 | Disables nearby towers and repeatedly disables the strongest towers | Spread towers at least two tiles from the road where possible; use several long-range damage dealers. |
The reference lists bosses as immune to Sniper Killshot, stun and snowball effects, with abilities dealing 90% less damage. Gauss is also treated differently from other towers in the general boss rules, so do not assume every tower or ability has ordinary effectiveness.
Encounter tactics
How to beat each boss
Broot is the first boss and the simplest mechanically. It is a single target, moves slowly and deals 100 damage if it reaches the base. Below 25% health it enters rage: it moves more slowly but heals for half of the damage it receives during the rage window. Save enough damage to burn through that final section instead of letting weak towers chip at it indefinitely. Freezing does not stop it, and abilities are poor substitutes for tower damage.
Stakey is the first major trap for new players. Its head begins completely protected, and the protection falls as body segments are destroyed. Body segments deal base damage, the tail has extra health, and removing segments makes the remaining snake faster. Do not set every tower to Last, because the tail is less useful to destroy and does not slow the boss. Cannon can hit multiple segments, while Sniper can contribute against the head once its protection is reduced. Poison is a poor choice because Stakey is immune to Venom’s poison damage.
Constructor punishes slow damage. It creates one Regular, one Fast and one Strong enemy every five seconds and becomes invulnerable during that action. It also creates larger groups at 75%, 50% and 25% health. The spawned enemies are selected from the level’s available enemies, with the three basic types added to the possible pool. Kill it quickly rather than trying to outlast its spawns. Sniper is a safe recommendation; Minigun can outperform it when the map gives the tower enough range and uptime.
Mobchain has two phases. In phase one, its head cannot be targeted and only the body can be damaged. A body part becomes highly resistant to bullets and explosions below 66% health, then becomes highly resistant to everything except bullets and explosions below 33%. Once every body part is gone, the head becomes vulnerable and colored ghost segments appear with icons showing their preferred tower type. Destroy those segments before the head consumes them to heal. Freezing and Blast do not solve this fight, so bring varied tower types and use Tesla or Minigun when available.
Metaphor is the final documented storyline boss and appears at wave 100 on 5.8. Its one-tile aura disables nearby towers. Each time it loses another 25% of its health, it disables the three strongest active towers, based on tower upgrade level and experience level, and those towers remain disabled until Metaphor dies. Smaller gray spiders distract defenses. Build multiple moderately upgraded towers instead of putting all power into three highly upgraded towers. Keep critical towers off the road, use long-range attackers, and avoid Blizzard or Windstorm, which have no effect according to the reference.
Map mechanics
Boss waves, boss tiles and random encounters
On custom maps without a special boss configuration, bosses normally appear no earlier than wave 40 and then every 20 waves. A Boss tile can replace that default behavior. The No bosses tile removes bosses but reduces score, mining speed and loot rarity. Rare makes bosses much less frequent. Marathon limits the map to one boss type and also reduces score and loot rarity. Hard makes bosses more frequent and increases score and loot rarity. The exact wave sequence is shown in the tile’s in-game configuration, so check it before starting a serious run.
Boss tiles can be obtained through enemy loot, chests and tile packets, with some variants coming from Lucky Shot. They are not simply cosmetic map pieces: choosing one changes the risk and the reward. For progression or a first clear, No bosses can make a difficult custom map manageable. For farming or leaderboard attempts, compare the score and loot modifiers against your ability to survive the extra encounters.
A separate random encounter can appear after wave 7. A flying white-winged scroll circles the portal for about 20 seconds. Tapping it may offer a challenge that summons a random star-marked boss. That boss has a randomly selected tower above it; the marked tower deals increased damage while other towers deal only a small fraction of normal damage. Defeating the challenge boss gives Accelerators. If it reaches the base, nothing happens, so this encounter is optional rather than a normal base-damage threat.
The random challenge boss is explicitly documented as dropping Accelerators. For the five named campaign bosses, available references confirm progression and ordinary end-of-game rewards but do not provide a dependable boss-by-boss fixed drop table. Treat claims about guaranteed unique items or exact drop rates as unverified unless the current game client shows them.
Practical preparation
A reliable boss-run checklist
Before the boss wave, open the portal or wave information and confirm the boss, supporting enemies and air units. Upgrade the damage dealers that can actually target the boss, but do not spend every coin on one tower when the encounter can disable, resist or ignore it. Leave room for emergency towers and avoid building critical attackers directly beside the path when Metaphor is possible.
For segmented bosses, decide whether your targeting priority is body, head or a displayed weak part. For Stakey, body-first is normally correct. For Mobchain, use the first phase to clear the body and the second phase to match each colored part with the appropriate tower. Against Constructor, do not pause to chase every spawned enemy if that lets the boss survive longer; add crowd control for the escorts, but keep the boss under concentrated fire.
Abilities are best treated as support rather than the main answer because bosses take greatly reduced ability damage. Use them to rescue the base, clear escorts or exploit a confirmed boss weakness, not as a substitute for the tower composition. After a failed attempt, compare the boss’s arrival wave, your strongest tower’s uptime and the number of enemies that leaked. Usually one of those three tells you whether to save more economy, change targeting or diversify damage.
Related modes
Daily quests, level 6 and developer content
Daily quests are special maps available for one day and reset at 00:00 GMT according to the reference. Researches and trophies are not counted in their normal conditions, and a quest can offer temporary access to towers or features that newer players have not unlocked. That is why a daily quest guide cannot safely prescribe one permanent build for DQ1, DQ5, DQ8 or DQ12: inspect the base effects, allowed tools, portals and bonus choices first.
The current indexed level overview lists campaign levels through 6.6, plus Rumble and Dev as endgame entries. The final storyline boss reference says defeating Metaphor leads to access to developer mode and, after completing the relevant research, Endless mode. Those modes are separate from the five standard campaign boss introductions, so a guide that calls Rumble or Dev a sixth campaign boss is mixing categories.
The boss system is version-sensitive. Update 1.9.0 specifically changed boss health and movement, while 1.9.2 added the optional random encounter. Use the in-game wave preview and boss panel as the final authority if they differ from an older reference.
FAQ
Common questions
Where is the first boss?
Broot is the first named campaign boss and first appears on level 1.8. It is a slow single target, but its rage phase below 25% health can still end an underpowered run.
How do I beat the boss on level 2.8?
Defeat Stakey’s body segments before relying on damage against the head. Use area damage such as Cannon or Tesla to remove segments, then concentrate strong single-target damage on the head. Do not prioritize the tail with every tower because destroying it does not slow the snake.
Why is the boss on 4.8 barely taking damage?
That is usually Mobchain’s phase-one resistance. Its head is invulnerable until all body parts are destroyed, and body parts gain strong resistance thresholds. Change tower types as the thresholds appear, then use the displayed tower weaknesses against the phase-two ghost parts.
Can I remove bosses from a custom map?
Yes. The No bosses tile removes boss spawns, but it applies penalties to score, mining speed and loot rarity. It is useful for learning a map or completing non-boss objectives, not for maximizing boss-related rewards.
Do campaign bosses drop a unique item?
No fixed boss-specific item table is reliably verified in the available references. The documented special drop is from the optional random challenge boss, which gives Accelerators. Check the current end screen and client data for exact campaign rewards.
Sources
What we checked
Official listings establish current availability and product facts. Community pages are used for mechanics and build history, then labeled separately.
- OfficialOfficial Steam announcement: update 1.9.0 and boss balance changes
- OfficialOfficial Steam announcement: update 1.9.2 random encounters
- CommunityCommunity reference: bosses overview and shared boss rules
- CommunityCommunity reference: individual boss behavior and counters
- CommunityCommunity reference: boss tiles and wave configurations
- CommunityCommunity reference: daily quests and reward structure