Octo Tank

The Octo Tank is one of the two final upgrades from the Quad Tank which is available at Level 45. It cannot upgrade further. On July 30th, 2016 it was nerfed, which reduced its and the Triple Twin’s health.

Design
It features a circular body surrounded by eight evenly spaced Barrels (spaced exactly 45 degrees apart).

Technical
The Octo Tank’s Bullet Damage gets yet another debuff. All of its other features are identical to the Quad Tank, except for the fact it has twice as many Barrels, giving the tank more area coverage rather than coverage from a single line of fire. It has no recoil, as all recoil is canceled out with the barrel opposite it.

Strategy

 * Strong Against: Multiple enemies, slow melee tanks.
 * Weak Against: High DPS, focused firing tanks, Destroyer branch, fast melee tanks, Drone users.

As the Octo Tank

 * Recommended builds include a glass cannon or general upgrades. A glass cannon build concentrates on Bullets and not on health Stats, and is vulnerable to fast rammers such as the Booster.
 * Another good build is the Hurricane, which is generally constitued like that : x/x/x/0/7/7/7/7. The low bullet speed creates a wall of bullets that is hard to penetrate, and it can corner enemies with its high movement speed. Due to the bullet-wall formation, it is near impossible to shoot between the cannons, unlike a normal build such as the above.
 * 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 very high Body Damage which might kill you instantly. However, you can catch unsuspecting prey by increasing Max Health and Body Damage in substitution with Bullet Speed and Movement Speed.
 * A good strategy for this tank is to turn Auto Fire and Auto Spin on, making it nearly impossible for rammers and any low Bullet Penetration tanks to kill you. This is also useful for farming pentagons.
 * 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.
 * As the Octo Tank in any team mode, if you max your Bullet Penetration and Damage, and head to the Pentagon Nest, you can act as a shield for the whole area. An Octo Tank needs its team too or else it will be vulnerable as someone could kill it easily using a Twin-class or Gunner-class tank.
 * You can counter low-Level Snipers with not fully upgraded Bullet Stats, but not Destroyers, Hybrids or Annihilators.
 * In Team DM modes, try to make a team that includes at least one Trapper, one high DPS tank like the Triplet, and one Drone user. This will maximize your chances of survival, as these are all tanks you would have trouble killing if they were the enemy.
 * Octo Tanks are similar to the Trapper, especially the Tri-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.
 * Get at least 3 or 4 people on your team to gather near the enemy base, and become Octo Tanks. Then, turn on auto spin and auto fire. This will force newly spawned players to stay in their base, while others can kill the better players on the enemy team. Be wary; this may cause a degree of lag. Even Triplets and Sprayers will be unable to touch the team, and only another team of high ROF tanks will be able to counter the Octo Tanks.
 * A highly effective build 0/5/0/1/7/7/6/7, the Hurricane build, is effective at countering rammer tanks and can flee easily from high ROF tanks. Against rammer builds, it can constantly chase them and if the rammer decides to double back and ram into you, your bullets can form a defensive shield due to the slow bullet speed, and easily repel the attempt. Only Boosters with 7 reload and movement speed are likely to escape the Octo Tank. This build even allows the Octo Tank to survive one shot from a Destroyer bullet! This build, along with skill, easily gets players to over 600k score.

Against the Octo Tank

 * This can be very dangerous due to the barrels surrounding it making it harder to approach. However, 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.
 * To counter an Octo Tank, use tanks from the Destroyer or Sniper branches. 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 Overlord or Overseer can use their Drones to flank the Octo Tank through the gap between its Barrels.
 * You can also team against Octo Tank with others and take it out.
 * Heavy concentrated fire from the Machine Gun or the Sprayer can easily wipe out 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 builds is 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. The opposing tank runs the risk of being hit in the flank by projectiles if this does happen.
 * Penta Shots work quite well against Octo Tanks. The high DPS and slightly-concentrated fire of the Penta Shot can easily out-penetrate the Octo Tank, while decreasing the chances of flanking if/when the Octo Tank does Auto Spin and Auto Fire.
 * Trapper classes can block incoming bullets and slowly approach the Octo Tank, and thus harm it. A good example of this is the Mega Trapper, which can shoot tough and scary mega traps to push to the Octo Tank.

History

 * In very old versions of Diep.io, the Max Level was 60, and the path to get the Octo Tank was like this: Tank → Twin → Triple Shot → Quad Tank → Octo Tank.
 * Therefore, at that time it was a Tier 5.
 * Before August 15th, it branched off the Twin Flank at Level 45, it was then removed by it's upgrade and replaced with Battleship. It now only branches off Quad Tank.

Octotank       pt-br: