Octo Tank

Not to be confused with the Quad Tank, the unupgraded form of the Octo Tank.

The Octo Tank is a level 45 Tank and is upgraded from Quad Tank. It may not further upgrade.

Design
It features a circular body surrounded by eight evenly spaced barrels.

Technical
Similar to the Quad Tank, the Octo Tank has a slightly increased bullet damage than other tanks with the same bullet size, except for the Tank. All of its other features are identical to the Quad Tank, except it has twice the amount of barrels, giving the tank more area coverage rather than coverage from a single line of fire. It has no recoil.

Strategy

 * Strong Against: Multiple enemies, slow melee tanks
 * Weak Against: High damage per second, focused fire, Destroyer, fast melee tanks, tanks with drones

As the Octo Tank

 * Recommended builds include a Glass Cannon or General Upgrades. A Glass Cannon build concentrates on bullets and not health, and is vulnerable to fast rammers like the Booster.
 * An Octo Tank with general upgrades can generally defend well against anything, but is vulnerable to Machine Guns, Gunners, and any other tanks with high Reload speed and max Bullet Penetration.
 * An unskilled Tri-Angle or a Booster can be easily destroyed by an Octo Tank without taking much damage in return.
 * Maximizing your Bullet Penetration can balance your vulnerable body if you have low Body Damage, but beware of Boosters as they may have high Body Damage which might kill you instantly. However, you can catch unsuspecting prey by increasing health and body damage in substitution with bullet speed and movement speed.
 * A good strategy is to turn Auto Fire and Auto Spin on, making it nearly impossible for rammers and any low Bullet Penetration tank to kill you. This is also useful for farming.
 * Beware that the Octo Tank only fires one bullet in each direction, so it's not very easy to combat bullet spam, like Machine Guns, Sprayers or Triplets. If you turn on both auto keys, you can slightly counter the attack.
 * Streamliners may be a threat too, but without maximizing reload and penetration, they wouldn't.
 * Octotanks are similar to the Trapper, except that it has more range and more cannons, but no traps at its disposal. This makes you strong at long range area-denial, while being able to hit targets easily because you use bullets.
 * An Octo Tank can also use the "Hurricane Katrina" build by doing the following build: 1/4/0/0/7/7/7/7. The slow bullets make for accuracy and allows the player to defend itself against booster players.

Against the Octo Tank

 * To counter an Octo Tank, use Sniper or its upgrades. The Octo Tank can't counter your strong bullets, so you can easily hit and kill it.
 * Alternatively, a skilled Tri-Angle or Booster can dodge the storm of bullets, and ram the Octo Tank between the barrels. Beware when there are other tanks around, as ramming the Octo Tank will leave you low on health.
 * An easy way of defeating an Octo Tank is to use any focused firing tanks with max penetration and shoot in the little gaps between the barrels.
 * An Overlord or Overseer can use their Drones to flank the Octo Tank through the gap between its barrels.
 * An extremely easy way to counter an Octo Tank is by using the Destroyer branch's massive bullet penetration to pierce the storm of bullets and hit the tank.
 * You can also team up on an Octo tank with others and take it out.
 * Heavy concentrated fire from the Machine Gun or the Sprayer can easily wipe an overlooking Octo Tank. A high rate of fire, combined with a strong bullet penetration will obliterate the Octo Tank, as it lacks concentrated fire in one direction.
 * A Triplet with 1/1/0/7/7/7/7/3 or similar loadouts are also excellent for dealing with Octo Tanks, since the solid wall of projectiles can easily overwhelm the Octo Tank's projectiles. However, one must beware if the opponent's Octo Tank has Auto Spin on, since rotating while firing causes bullets to slightly curve and the player runs the risk of being hit in the flank by projectiles.

Trivia

 * In very old versions of Diep.io, the max level was 60, and the path to get the Octo Tank was : Tank → Twin → Triple Shot → Quad Tank → Octo Tank.
 * Before August 15th, it branched off Twin Flank.