Swarmer has been made unobtainable from the game as of the 26th of May 2020 as it was part of the Spring 2020 Event. Players with the item in question can continue using it, but you cannot obtain this item anymore, outside of limited-time promotional sales.
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This article is about Swarmer. You may be looking for Swarm.
OH NOES, THE BEES! Attack enemies with bees that do damage over time. Won Spring 2020.
The Swarmer is an event damage over time tower that could have been obtained by triumphing Eggy Island's Hard difficulty as part of the Spring 2020 Event. It could have also been bought via a gamepass for 350 during Spring 2020, and can most recently be bought again for 799.
The Swarmer deals damage by throwing beehives and later by firing bees, additionally applying a single stack of bees on an enemy. The struck enemy is then inflicted with the Bee Debuff effect, taking damage over time without requiring the Swarmer to directly attack it. The bee stack has a set duration for each level, in which it will then decay with the individual Bee Debuff effect expiring along with it. The enemy will be damaged each Tick, the interval between each sting for a given amount of time, known as Sting Time. This functions similarly to other forms of tick damage, such as the Pyromancer's burn damage.
The Swarmer can apply multiple bee stacks at a single enemy, with each Swarmer having a cap that increases every level. Other Swarmers can contribute to the stack, exceeding the initial maximum stack in an instance where there is only one Swarmer, and multiple bee stacks will inflict all of their collective DPS on a single target. When there are multiple stacks applied, Sting Time does not apply to each one. Instead, after the first stack's Sting Time ends, a single stack will be removed and the timer will restart. The Bee Debuff effect will persist so long as there is at least one extant stack. There is a limit of 10,000 stacks per enemy. This can damage Lead enemies and bypasses Defense.
The Swarmer additionally has the Bee Swarm Grenade (internally just Swarm) ability, where it throws a grenade that deals AOE damage and applies a single stack of bees to all enemies caught in the explosion radius. The Bee Debuff's stats from Bee Swarm Grenade is directly proportional to the current level of the Swarmer that it was thrown from. The bee swarm grenade's explosion deals explosion damage, bypassing defense, dealing damage to Lead while also having no damage drop off.
Due to its stacking capabilities, the Swarmer is generally considered to be a boss killer, being able to do quite high DPS when a lot of Bee Debuff effects are stacked. Additionally, it also has decent early game potential. It, however, is heavily hindered by its lack of detections and generally not being that strong with a low amount of extant bee stacks.
Throws a bee swarm grenade that deals area damage and inflicts the stinging effect on enemies that were hit by it, dealing damage over time. The explosion deals damage to Lead, bypasses defense and has no damage drop off.
Statistics
To see all the previous statistics of this tower, see the history page.
The Swarmer is generally not the most effective option for earlier parts of the game due to its slow firerate, rather low range and low sting damage.
If used, it should be set to Strongest so that it can hit as many enemies as possible or prioritize stronger enemies to apply more bee debuff effects to. First Enemy targeting would make it always target the first enemy, which can be ineffective as some damage will be wasted if you have more than enough stacks.
Later on, as Swarmer excels in single target damage, it is best to keep all Swarmers placed on Strongest.
It can, however, become a very strong tower once higher health enemies such as the Fallen Squire and Slow Boss start to appear.
The Swarmer will reapply the bee debuff effect to an enemy if it attacks the same enemy, allowing it to be stacked.
Only the sting time for one effect can be active on an enemy. If there are 100 stacks, the earliest one will be active. This effectively means that constantly applying the effect can extend it.
This allows it to reach extremely high DPS values, even being able to take down the bosses like the Fallen King and Molten Warlord somewhat quickly. For example, ten Level 5 Swarmers, after firing at a boss for just 12 seconds, will have applied roughly 100 stacks of bees, dealing a total of 400 DPS from just the incomplete stack alone.
The Commander can be extremely useful with the Swarmer, as it allows it to apply its effects at a faster rate, making its rampup much faster.
The DJ Booth can be used to boost it, however its effects are far less effective on it due to the Damage Buff only buffing its main attack (which has its damage revoked at Level 3) and Bee Swarm Grenade, so it is recommended to use Purple track instead if the Swarmer is your only or primary DPS source.
The Green track can additionally help with affording the extreme amount of Swarmers required to reach the tower's full potential.
The Bee Swarm Grenade ability can be used to quickly apply the stinging effect to multiple enemies, allowing the Swarmer to start dealing more damage faster.
If multiple Swarmers are placed down, using abilities from multiple of them can allow you to mass apply the effect to multiple enemies at once. Additionally, as only one effect can expire at once, it will last for quite a while before it ends.
The Swarmer is unaffected by some debuffs applied by enemies, but not all. For example, Wox the Fox will be unable to apply the Scared Debuff to it, but the Boomer can apply all its debuffs without any issues.
Trivia
The original design of Swarmer is based on R2DA'sSwarmer in name and appearance.
Additionally, the Swarmer's Level 5 outfit was very similar to R2DA's Beekeeper Suit.
The store description is taken from a scene involving Nicholas Cage in the film The Wicker Man.
Immediately after the Swarmer's addition, it could have been bought for 2,500.
However, this was soon removed, and anyone who acquired the Swarmer this way was refunded.
The Swarmer's stinging mechanic was originally a bug that allowed the Swarmer to stack the effect multiple times. This would be removed in v1.9.0 with the tower debuff reworks, though later brought back in v1.52.0.
The Swarmer has the highest cost efficiency in the entire game, at $3,808.63 on Level 5.
The Swarmer is currently the only tower to have one of its upgrades remove its direct damage.
Update History
For previous cosmetic variations, see the gallery page.
Bug: Swarmer can use its Beehive Grenade ability on an enemy that is currently being stung.
Bug: Swarmer's stinging effect can stack.
Bug: Selling a Swarmer allows other Swarmers to attack an enemy the sold Swarmer applied the stinging effect to, with the normal attack and Beehive Grenade ability.
Splash damage reworked. Now the explosion is separated into two spheres. Inner sphere deals 100% of the stated damage while the damage in the outer sphere decreases linearly.
Bug: The Swarmer's total damage counter will continue to rise even if all enemies are dead, until the sting time ends.
A single Swarmer now can stack its stinging effect on enemies.
Bugfix: Swarmer will now target enemies in its range that are not being stung over enemies that are being stung, though once there are no more enemies without the effect in range it will keep attacking enemies that are being stung.
Swarmer is now purchasable through a gamepass for 799.
Main attack now deals damage.
Now always target enemies based on its targeting rather than trying to apply its debuff to every enemy at once.
Effects from multiple Swarmers now stack.
Each individual Swarmer now has a stack limit of 150.
Stack limit for all Swarmers is 5,000.
Stack count is now displayed under enemy health.
Bee Swarm Grenade now can be thrown at enemies that are being currently stung.
Swarmer no longer waits five seconds for an enemy to enter its range after Bee Swarm Grenade is used, now it will throw its grenade at a random spot on the path if there are no enemies in range.
Now only one stinging time from an effect is active at once for an enemy. Previously, another effect being applied would extend the effect and the entire stack would disappear once it ends.
Both main attack and Bee Swarm Grenade now trigger Firework Technician fireworks.
Name changed from Improve Handling to Agressive Bees.
Level 3
Cost increased from $500 to $1,500.
Firerate changed from 1.525 > 1.025 to 1.525 > 1.275.
Range increased from +2 to +3.
Damage increased from +0 to +6.
Sting time changed from 4 to 4.5 > 5.25.
Bee Swarm Grenade unlocked, moved from Level 4.
Explosion range decreased from 10 to 6.
No longer has damage drop off.
Name changed from Beehive Grenade to Bee Swarm Grenade.
Name changed from Bee Gun to Bee Certified Weapons.
Level 4
Cost increased from $1,400 to $3,000.
Firerate changed from 1.025 to 1.275 > 1.025.
Range increased from +0 to +2.
Damage increased from +0 to +5.
Bee damage decreased from +2 to +1.
Tick changed from 0.75 > 0.5 to 0.75
Sting time changed from 4 > 6 to 5.25 > 5.5.
Grenade damage increased from +0 to +20.
Explosion range changed from 10 to 6 > 7.
Level 5
Cost increased from $4,000 to $6,000.
Firerate changed from 1.025 > 0.525 to 1.025 > 0.775.
Range decreased from +2 to +0.
Damage increased from +0 to +10.
Bee damage decreased from +2 to +1.
Tick changed from 0.5 > 0.25 to 0.75 > 0.5.
Sting time changed from 6 > 8 to 5.5 > 8.
Grenade damage increased from +0 to +20.
Explosion range changed from 10 to 7 > 8.
Bug: Swarmer will often fire ahead of the enemy instead of at it, though this is purely visual.
Bug: Selling the Swarmer will not remove the stacks from an enemy, but it will make them deal no damage.
Bug: Swarmer is not affected by certain debuffs.
Bug: Swarmer is unaffected by stuns from legacy enemy if they are fired like a minigun or beam, examples include the Gunslinger, Warden and Minigunner enemies.
Bug: When in range of a Medic, it will be able to affect less towers with its Cleansing ability. Stacks with each Swarmer or other similarly bugged tower/skin in range.
Bug: When the Swarmer applies a stack to an enemy, every Swarmer that applies one afterwards will use the sting damage of that Swarmer instead of theirs sting damage.
Bugfix: Firerate is no longer twice as long.
Bugfix: Upgrade descriptions now properly list changes made to the tower.
Firerate changed from 1.525 > 1.275 to 1.5 > 1.25.
Bugfix: When the Swarmer is sold, the stings that are on an enemy actually deal damage.
Bugfix: Each Swarmer now can deal different sting damage values to an enemy instead of using the same one as the first Swarmer that fired at the enemy.
Notes
↑From Level 3, its Bee Swarm Grenade ability can indirectly hit hidden enemies, but this tower cannot directly target hidden enemies.
↑From Level 3, its Bee Swarm Grenade ability can indirectly hit flying enemies, but this tower cannot directly target flying enemies.
↑Due to bugs, it cannot be stunned by abilities fired like a minigun or ones that are lasers. This includes the legacy Templar, legacy P3NGU, Warden, Minigunner, Gunslinger's Crossbones Crossfire and Nuclear Monster's Nuclear Beam.
↑This ability has two names, Bee Swarm Grenade seen in its upgrade descriptions and Swarm, seen in pop-up messages and certain menus.
↑Total Elapsed Damage is (Sting Time ÷ Tick) × Bee Damage. In cases where Sting Time ÷ Tick results in a number that is not a full number, such as 7.33, it should be rounded down, in the previous example that being 7.
↑DPS assumes that only one enemy is currently being stung and only one stack is applied. It is calculated as (Damage ÷ Firerate) + (Bee Damage ÷ Tick)
↑How much DPS is added every second through it applying bee stacks. It is calculated as (Bee Damage ÷ Tick) ÷ Firerate
↑DPS when every single stack is applied for one Swarmer. It is calculated as (Damage ÷ Firerate) + [(Bee Damage ÷ Tick) × Stack Limit]
350 during Spring 2020, and can most recently be bought again for 
