Spike Factory (BTDi)

The almighty Spike Factory returns in Bloons Tower Defense i. It will randomly place spikes around itself, popping bloons that try to pass by it. It has very powerful cross-pathing benefits, giving its higher tiers hundreds of millions of DPS. It is one of the strongest towers in late-game.

And you thought Perma-Spike was OP...

Path 1
These upgrades focus on popping as many bloons as possible. Place these at the end to pop any bloons that are about to escape.

Path 2
These upgrades increase the production speed and damage to MOAB-class bloons. Place them at the beginning to inflict rapid damage.

Path 3
These upgrades support the tower, increasing damage done to all types of bloons. These can be placed anywhere to assist other towers.

{| class="article-table" cellspacing="1" cellpadding="1" border="1" align="left" ! ! scope="row" style="text-align:center;" | Path 1 ! scope="col" style="text-align:center;" |Cost ! style="text-align:center;" |DPS
 * 1
 * scope="row" style="text-align:center;" |
 * scope="row" style="text-align:center;" |

Bigger Stacks
Spike piles are bigger and can pop 10 bloons. 2
 * style="text-align:center;" |$660
 * style="text-align:center;" |x2
 * 2
 * scope="row" style="text-align:center;" |
 * scope="row" style="text-align:center;" |

Much Bigger Stacks
Spike piles are even bigger and can pop 20 bloons. 4
 * style="text-align:center;" |$1,400
 * style="text-align:center;" |x2
 * 3
 * scope="row" style="text-align:center;" |
 * scope="row" style="text-align:center;" |

Spiked Balls
Spike Factory now produces giant spiked balls instead of regular spikes. Each spike ball can pop 50 bloons. 10
 * style="text-align:center;" |$4,800
 * style="text-align:center;" |x2.5
 * 4
 * scope="row" style="text-align:center;" |
 * scope="row" style="text-align:center;" |

Oversized Spikes
Giant spike balls can withstand the popping of 250 bloons each. 50
 * style="text-align:center;" |$35k
 * style="text-align:center;" |x5
 * 5
 * scope="row" style="text-align:center;" |
 * scope="row" style="text-align:center;" |

Juggernaut Spikes
Produces Juggernaut Spikeballs and places them directly on the track. Each ball can now pop 4,000 bloons. 800
 * style="text-align:center;" |$725k
 * style="text-align:center;" |x16
 * 6
 * scope="row" style="text-align:center;" |
 * scope="row" style="text-align:center;" |

Planetary Spikes
Enormous Planetary Spikes can hold off up to 80,000 bloons each. $16M 16k
 * style="text-align:center;" |
 * style="text-align:center;" |x20
 * 7a
 * scope="row" style="text-align:center;" |
 * scope="row" style="text-align:center;" |

Universal Spikes
Indestructible spheres of pure popping power. Each ball is able to stop 10,000,000 bloons. 2M
 * style="text-align:center;" |$2.3B
 * style="text-align:center;" |x125
 * 7b
 * scope="row" style="text-align:center;" |
 * scope="row" style="text-align:center;" |

Planet Busters
Upon destruction, spiked balls will detonate a massive plasma bomb, blasting two million layers off anything in a 300-pixel radius. 400k
 * style="text-align:center;" |$2.5B
 * style="text-align:center;" |x25
 * }
 * }

{| class="article-table" cellspacing="1" cellpadding="1" border="1" align="left" ! ! scope="row" style="text-align:center;" | Path 2 ! scope="col" style="text-align:center;" |Cost !DPS
 * 1
 * scope="row" style="text-align:center;" |
 * scope="row" style="text-align:center;" |

Increased Production
Spike piles are produced 50% faster. 1.5
 * style="text-align:center;" |$330
 * style="text-align:center;" |x1.5
 * 2
 * scope="row" style="text-align:center;" |
 * scope="row" style="text-align:center;" |

High-Efficiency Spikes
Monkey engineers have added sprockets, dongles, and widgets, decreasing production time by 50%. 3
 * style="text-align:center;" |$1,080
 * style="text-align:center;" |x2
 * 3
 * scope="row" style="text-align:center;" |
 * scope="row" style="text-align:center;" |

Ultra-Speed Spikes
Spikes are produced twice as fast and launched at bloons. 6
 * style="text-align:center;" |$2,400
 * style="text-align:center;" |x2
 * 4
 * scope="row" style="text-align:center;" |
 * scope="row" style="text-align:center;" |

MOAB-SHREDR Spikes
Super-Hard-Rending-Engine-Driven-Razors are even quicker to produce and inflict quintuple damage to MOAB-class bloons. 60
 * style="text-align:center;" |$48k
 * style="text-align:center;" |x10
 * 5
 * scope="row" style="text-align:center;" |
 * scope="row" style="text-align:center;" |

Supersonic Spikes
Spikes are produced ridiculously fast and do 40x damage to MOABs. 960
 * style="text-align:center;" |$870k
 * style="text-align:center;" |x16
 * 6
 * scope="row" style="text-align:center;" |
 * scope="row" style="text-align:center;" |

Spike Storm
Spikes deal 500x damage to MOABs. The Spike Storm ability launches hundreds of spike piles all over the screen. $14M 12k
 * style="text-align:center;" |
 * style="text-align:center;" |x10
 * 7a
 * scope="row" style="text-align:center;" |
 * scope="row" style="text-align:center;" |

Spike Tornado
Ability is 3x stronger and its cooldown is reduced by 75%. Spike piles are produced 10 times faster and deal 7,500x damage to MOABs. 1.8M
 * style="text-align:center;" |$2.5B
 * style="text-align:center;" |x150
 * 7b
 * scope="row" style="text-align:center;" |
 * scope="row" style="text-align:center;" |

Spike Hurricane
Ability is automatically activated 10 times every round, distributed evenly throughout the spawns. Spike piles deal 62,500x damage to MOABs. 1.5M
 * style="text-align:center;" |$2.1B
 * style="text-align:center;" |x125
 * }
 * }

Path 3
{| class="article-table" cellspacing="1" cellpadding="1" border="1" align="left" ! ! scope="row" style="text-align:center;" | Path 3 ! scope="col" style="text-align:center;" |Cost !DPS
 * 1
 * scope="row" style="text-align:center;" |
 * scope="row" style="text-align:center;" |

Hardened Spikes
Spikes cut through the outer layers of bloons more easily, dealing double damage to armored bloons. 2
 * style="text-align:center;" |$500
 * style="text-align:center;" |x2
 * 2
 * scope="row" style="text-align:center;" |
 * scope="row" style="text-align:center;" |

White-Hot Spikes
Spikes are heated to extreme temperatures, popping 2 layers, melting through Metal Bloons, and doing triple damage to armored bloons.
 * style="text-align:center;" |$2,000
 * style="text-align:center;" |x3

6
 * 3
 * scope="row" style="text-align:center;" |
 * scope="row" style="text-align:center;" |

Resilient Spikes
Spikes are more resilient, lasting 50% longer and popping 5 layers each.
 * style="text-align:center;" |$7,100
 * style="text-align:center;" |x2.5

15
 * 4
 * scope="row" style="text-align:center;" |
 * scope="row" style="text-align:center;" |

Perma-Spikes
Spikes are almost permanent, doing 15 damage and lasting twice as long.
 * style="text-align:center;" |$26k
 * style="text-align:center;" |x3

45
 * 5
 * scope="row" style="text-align:center;" |
 * scope="row" style="text-align:center;" |

Deadly Spikes
Spring-loaded Deadly Spikes can pierce through 300 layers each.
 * style="text-align:center;" |$825k
 * style="text-align:center;" |x20

900
 * 6
 * scope="row" style="text-align:center;" |
 * scope="row" style="text-align:center;" |

Assassin Spikes
The pinnacle of anti-armor technology, Assassin Spikes rip through 6,000 layers per spike and cannot be evaded. $18M 18k
 * style="text-align:center;" |
 * style="text-align:center;" |x20
 * 7a
 * scope="row" style="text-align:center;" |
 * scope="row" style="text-align:center;" |

Genospikes
Mass Bloon genocide. 3.6M
 * style="text-align:center;" |$3.5B
 * style="text-align:center;" |x200
 * 7b
 * scope="row" style="text-align:center;" |
 * scope="row" style="text-align:center;" |

Electrospikes
Spikes will completely destroy the shield of any bloon that comes in contact with them. They do 500x damage to shields and Auracrysts. 9M
 * style="text-align:center;" |$3.8B
 * style="text-align:center;" |x500
 * }
 * }