Deadly Spikes

"Extra deadly spikes can pop through 2 layers per spike and last another round."

- BTD6 description as of Version 20.0

Deadly Spikes is the Tier 4 upgrade of Path 3 for the Spike Factory in Bloons TD 6. It allows all spikes of the Spike Factory to pop two layers instead of one, effectively doubling its popping power. Additionally, all spikes now last for 3 rounds instead of 2. Like Long Life Spikes, spikes dispensed from Deadly Spikes last for 140 seconds.

It costs $2,975 on Easy, $3,500 on Medium, $3,780 on Hard, and $4,200 on Impoppable.

Tower Prices

 * Updated as of Version 29.4

Summary
Deadly Spikes is a somewhat situational upgrade whose benefits rely primarily from long-term stalling, and it is prominent compared with Long Life Spikes. The upgrade alone is more expensive than adding an external buff, but there can be a few select occasions where just adding this upgrade can be useful. For example, it can tank leaking Camo Bloons reasonably well, but it will find difficulty beating the Camo Ceramics on Round 51 or the rushes of Camo Rainbows on Round 56 if not enough stalling is done. But, if stalling is done properly, it can easily tank a good chunk of camo bloons if granted external support.

Similar to Long Life Spikes they require external support to be closer to the viability of Spiked Balls later in the game. Berserker Brew and Stronger Stimulant are good examples of external supports, which providing it with +1 damage and +2 / +3 pierce.

This upgrade enhances Spike Factory's stockpiling potential and it is recommended to be used for defensive purposes to maximize its efficiency.

Spikes from this factory last in between rounds even longer but their lifespan is unchanged meaning Spike Factory eventually reaches its stockpile cap.

Tips

 * In most situations, it's better off buying Deadly Spikes only when Berserker Brew is not available. Berserker Brew adds +1 damage, +2 pierce, and ~+10% attack speed for the Spike Factory. Note that 3-0-0 Berserker Brew costs just $2400 on Medium; saving $1100 plus extra benefits, in spite of the brew effect having only 62.5% uptime.
 * Deadly Spikes is not reliable at soloing Camo Bloon rounds, particularly Rounds 51 and 56. It is better off choosing an alternate option to counter Camo Bloons, such as a 4-x-x Bloonjitsu or by adding in a cheap form of decamo such as Submerge and Support or Counter-Espionage.
 * Without Buffs, on average, and against non-ceramics and non-fortified, a 0-2-4 Deadly Spikes have the same total damage potential as a 3-2-0 Spiked Balls. However, when both are paired with Berserker Brew, 0-2-4 Deadly Spikes damage potential becomes much stronger, or as strong as the 3-2-0 Spiked Balls, only losing against Ceramics. One other advantage with Deadly Spikes is that they don't need to replenish piles whenever a round starts.
 * Again, like Long Life Spikes, it's better off going for a 0-2-4 Deadly Spikes instead of a 2-0-4 Deadly Spikes, because the spikes refresh faster and a 0-2-4 Deadly Spikes synergizes better with Alch buffs.

Trivia

 * This upgrade is the second upgrade in the Bloons TD series to use the word "Deadly", the first being "Deadly Precision".
 * The Deadly Spikes round lifespan buff in Version 21.0 also indirectly affects Perma-Spike.