Psi

"A gifted monkey child, Psi uses only the power of the mind to destroy Bloons from the inside out."

- BTD6 description

 is a Hero in Bloons TD 6 who was added to the game in update 26.0. They use psychic vibrations to stun and destroy singular Bloons but initially cannot affect Purple, Lead, and Ceramic or stronger. They are one of the only heroes to detect Camo Bloons at base level, the others being Ezili and Sauda.

Psi's psychic attack will attack bloons from any range based on their target priority, and the attack always ignores Line of Sight. Once a bloon is affected by their psychic attack, the bloon will become shocked in place and eventually die off in full. Other towers will no longer target shocked bloons, as the affected bloons are already instakilled but visually are going through a process of being instakilled. Psi's psychic attack can be compared to a Druid of the Jungle but much stronger and faster, as Psi's attacks do not have hardcoded targeting and can be upgraded to gain secondary effects.

There is currently a misconception that from Level 4, bloons that Psi target are able to affect bloons that touch them. This is not the case, as instead the upgrade gives Psi the ability to affect one other bloon in a small radius close to the original target, similar to Ezili.

Psi's attack is unaffected by Acidic Mixture Dip, so leveling is required to pop all bloon types. Monkey Intelligence Bureau allows Psi to target and affect Leads and Purples but not Ceramics. At maximum level, Psi can instakill ZOMGs and DDTs, but will never harm BADs at all.

Psi costs $680 on Easy, $800 on Medium, $865 on Hard, and $960 on Impoppable. If Hero Favors is enabled, Psi will cost $610 on Easy, $720 on Medium, $780 on Hard, and $865 on Impoppable. Psi can be unlocked with a one-off purchase of 5000.

In 30.0 update Psi received new skin called "Psimbals" changing their appearance, quotes and making them a bit more energetic.

Upgrades
Psi upgrades automatically after being placed. Their XP requirement ratio is 1.5x, equivalent to Benjamin's leveling speed.

Cosmetics
Psi has different cosmetics that can be bought to add visual flair to them. These are purely visual and do not influence how they perform in-game. Hero Skins for Psi are available once they are unlocked.

Skins
Psi has one hero skin available. Their one hero skin is Psimbals, which dons them as a cymbal-and-bass-drum-playing band musician, later promoting into a multi-instrumental band conductor.

Pets

 * Psi Bison Pet PsiBisonPetIcon.png
 * Description: An exemplary specimen of the even-toed ungulate genus, which Psi happens to find mega adorable. Original Psi only ;)
 * Added: 29.0
 * Additional notes:
 * Short name: Psi Bison
 * Bison walks around and makes sounds.
 * Trophies: 110

Profile Pictures

 * Custom Avatar - Action Psi ProfileAvatar51.png
 * Description: Being at one with the universe all the time doesn't mean Psi can't have a little fun now and then! Rock this awesome Psi avatar to show them some love.
 * Added: 29.0
 * Additional notes:
 * Short name: Action Psi Avatar
 * Depicts Psi Level 20 empowered.
 * Trophies: 10

Original Psi
When Selected on the Heroes menu:
 * "I am both here and everywhere."

When Placed:
 * "I am both here and everywhere."
 * "With focus, we act as one."

When Selected:
 * "Yes..."
 * "Yes?"
 * "Sensing."
 * "Fellow traveler..."
 * "What do you seek?"
 * "What do you seek?" (Different tone)
 * "No further."'' (when annoyed)
 * "Ripples on the surface do not change the stillness of the lake."'' (when really annoyed)

Leveling Up:
 * "My awareness grows."
 * "My awareness grows." (Different tone)
 * "I sense more fully."
 * "I sense more fully." (Different tone)
 * "Ahh...knowledge."
 * "Ahh...knowledge." (Different tone)
 * "Inner peace."
 * "More shall come..."
 * "From knowledge...to understanding..." (Level 20)

When MOAB Class bloons Appear:
 * "Be wary." (MOAB appearance)
 * "Red is the color of destiny." (BFB appearance)
 * "Behold the bloated green of envy." (ZOMG appearance)
 * "You cannot have light without darkness." (DDT appearance)
 * "Size matters not." (BAD appearance)

When a MOAB-Class Bloon is Destroyed:
 * "Even mountains crumble."
 * "There is no Bloon."

When activating Psychic Blast:
 * "Stillness."
 * "Hold."

When activating Psionic Scream:
 * "Begone!"
 * "Everything."

When Bloons Leak:
 * "Some leaves must fall."
 * "Some leaves must fall." (Different tone)

Psimbals
When Selected on the Heroes menu:
 * "Showtime, go time!"

When Placed:
 * "Showtime, go time!"
 * "Are you ready for a show?"

When Tapped:
 * "At your service."
 * "At your service." (Different tone)
 * "Step right up!"
 * "Tuned and ready!"
 * "Watch the instruments." (When annoyed)
 * "Let me work already!" (When very annoyed)

Leveling Up:
 * "I like the sound of that!"
 * "Pump up the volume!"
 * "Pump up the volume!" (Different tone)
 * "Better than ever!"
 * "Better than ever!" (Different tone)
 * "The band's all here!" (Level 20)

When MOAB Class bloons Appear:
 * "Talent scout!" (MOAB appears)
 * "Big red target!" (BFB appears)
 * "Increase tempo!" (ZOMG appears)
 * "Double time!" (DDT appears)
 * "Play your hearts out!" (BAD appears)

When a MOAB-Class Bloon is Destroyed:
 * "Now that's a finale!"
 * "Killer finish!"

When activating Psychic Blast
 * "Didn't listen!"
 * "Lock them down!"

When activating Psychic Scream:
 * "The show is over!"
 * "I do not play for you."

When Bloons Leak:
 * "Don't let the audience leave!"

Sounds
Other sound effects related to Psi that are not specifically their voicelines are shown here.

When activating Psychic Blast with Hero Voicelines off:
 * HeroIconPsi.png [pulsing energy]
 * HeroIconPsimbals.png [cymbals crashing]

When activating Psionic Scream with Hero Voicelines off:
 * HeroIconPsi.png [Sudden discord]
 * HeroIconPsimbals.png [Music burst]

Summary
Psi is mostly oriented as a support DPS hero. Their attacks are long-ranged and attack a limited number of bloons at a time, but can instakill with their base attack. Initially, they will struggle a lot against Ceramics and MOAB-class due to the slow leveling curve of Psi, but at much higher levels Psi becomes a very strong hero capable of doing a lot of damage. Psi has two abilities that also act as support, with Psychic Blast as a way to clump bloons up with a large stun wave, and Psionic Scream as a large-scale damage and blowback source. At maximum level, Psi is extremely powerful at anything below a BAD, and can even solo short but dense rounds such as Round 98 with a single ability use. That being said, a majority of that power comes from the Psionic Scream ability.

When it comes to synergies in-game, Psi works well as a supporting DPS to existing tower combinations. Psi comes with built-in camo detection and infinite range, and their abilities can help assist the defense whenever needed. Much of their true power comes behind higher levels, given their exponential power over each level, and as such faster leveling is essential for Psi's potential. Use of hero leveling boosts such as playing Intermediate+ maps (gives more XP at higher map difficulties), and adding a nearby Energizer are very helpful.

During the early-game, their expertise is much like the Sniper Monkey overall, excelling against spaced bloons and strong bloons alike, plus breezing through Round 24. During the mid-game, their most valuable role in that stage is to excel at handling Ceramics from underneath blimps, plus an available stun ability via Psychic Blast to clump up bloons. During the late-game, their Psionic Blast adds the majority of their power, clearing up many of the excessive bloons on screen. The best synergies with Psi include Ground Zero, First Strike Capability, and Energizer, which all in turn counter Psi's major weaknesses during later stages of the game.

Tips

 * Even though Psi has infinite range, they should still be positioned close to the track to utilize Psychic Blast.
 * Due to Psi's slow attack speed, they should not be completely relied on for damage output.
 * Using level 10 ability with a maxed Psi, you can annihilate rounds with large number of bloons like 96 and 98.
 * Psi can be targeted by brews from Berserker Brew and above but not Acidic Mixture Dip.
 * Target priority of Psi is very useful. Psi takes longer to take down stronger bloons, but faster on weaker bloons. They should be put on Strong to pick off stronger bloons at the cost of a slower rate, as instakilling strong bloons works with Psi's strengths, but they should be put on First to pick off bloons nearest to the exit. However, at Level 20 they will benefit better with Strong at all times to make use of the high damage to ZOMGs and DDTs.
 * Psi synergizes very well with Energizer, as Energizer makes up for Psi's weak mid-game and lets them scale better for late-game. That being said, such an investment is very expensive and doesn't necessarily fully cover the costs of manual upgrading Psi later on to defend against BFBs and above on CHIMPS Mode. On the bright side, it means abilities will recharge faster, such as their Psychic Blast and Psionic Scream abilities.
 * It takes time for Psi's instakill effects to pop bloons in their entirety. If Psi instakills an entire round, especially with their Psionic Scream ability, there is a time delay before ending the round. This is especially noticeable with Level 20 Psi one-shotting high-HP rounds such as Round 98.
 * Level 20 Psi is not useless against Round 100, as a properly timed Psi's Psionic Scream ability can instantly destroy the BAD offspring in one shot once the BAD layer pops.
 * Unlike other Heroes, Psi cannot directly attack the Golden Bloon, even at Level 20. Their Psionic Scream ability is also ineffective at any level.
 * Their Psychic Blast does stun the bloon for a significant period of time when it is caught in the blast radius.
 * Towers that are effective at handling blimps are the best synergies for Psi, especially during the mid-game. 4-2-0 Maim MOAB can stun the blimps to stall time to pop groups of blimps for the mid-game, while Ground Zero destroys various dense mid-game bloons with its ability. Psi during their moderate levels can assist at handling the Ceramics underneath the MOABs when set on Strong.
 * During the late-game, use typical counters to MOAB-class and Super Ceramics. As Psi is mainly a support DPS, they won't do much at killing stronger bloons until reaching much higher levels.
 * Ground Zero synergizes with Psi by destroying large groups of bloons and weaker blimps, or at least breaking blimps into more manageable clumps to pair with their Psionic Scream ability. For the mid-game, Ground Zero's ability can be used to handle overwhelming blimps and bloons during necessary emergencies, plus its main attack can dish some high damage so that Psi can focus attacks on more useful targets.
 * Perma-Spike can be paired with Psi to tank weaker bloons and counter DDTs before reaching Level 20. Its capability to tank weaker bloons is to reduce overdependence on Psionic Scream, as that ability has a long cooldown, while 0-2-5 Permaspike paired with Alch buff can counter DDT rounds such as Round 95.

Teasers
They were revealed on Twitter on May 20th, 2021, alongside their abilities.

Trivia

 * Psi uses they/them pronouns. This makes Psi the first original named character in the Bloons TD franchise to use gender-neutral pronouns.
 * BMO and Holiday BMO, characters from Bloons Adventure Time TD, also use gender-neutral pronouns among others, but they originate from Adventure Time and are not original Bloons TD characters.
 * Sergeant Monkey from Bloons TD Battles Mobile was also referred to using gender-neutral pronouns, but this was more likely because they were a computer opponent for the tutorial and not an actual character.
 * Psi was released in Version 26.0 on June 4, 2021, during Pride Month in the United States.
 * Psi's gender identity has not been confirmed. Ninja Kiwi "liked" a tweet from a fan asking if Psi is non-binary, making the possibility likely, but not definitive.


 * Psi Bison Pet's description has a wink emote placed after "Original Psi only"; this was likely a teaser from Ninja Kiwi regarding Psi's first hero skin that was added in Version 30.0, the update after the Psi Bison Pet was released. At the time, some of the BTD6 community wanted Psi to receive a hero skin.
 * Psi is the shortest base tower name in BTD6 (3 letters long).

Gameplay

 * Psi's instakilling methods on MOAB-class is a possible reference to a bug in Version 8.0 where Striker Jones Level 9+ (Level 5+ at present) + Druid of the Jungle allowed Druid vines to affect MOAB-class bloons, instantly destroying blimp layers on every shot. However, Psi can instakill MOAB-class in full with Level 14+.
 * Psi is the second hero to have infinite range basic attack after Benjamin's level 7 Bloon Trojan. As such, they also have a "dummy" range like Snipers or Dartling Gunners.
 * Psi's "dummy" range will allow Advanced Intel subs to target Camo Bloons within the range.
 * Psi cannot attack a B.A.D and will stay still if it is the only bloon present on the map.

Cultural references

 * The dots on Psi's forehead are a form of Jieba ritual received by Shaolin monks for finishing their training.
 * The dots also form the Greek letter "psi", or Ψ/ψ.
 * The line "There is no Bloon" references the "There is no spoon" scene from The Matrix.

Ninja Kiwi Blogs

 * According to Ninja Kiwi's 27th August 2021 blog, Psi is being employed as a child because of "pocket money." From another comment, they also meditate or read in their spare time.