The Quad Tank is one of the three current upgrades from the Twin and one of the four current upgrades from Flank Guard at Level 30. Quad Tank previously upgraded from the Triple Shot at level 45. It can upgrade further into the Octo Tank or Auto 5 at Level 45.
The Quad Tank has a circular base surrounded by four Cannons in a plus shape, designed such that recoil is canceled out because of the position of its weapons, like the Flank Guard, the Twin Flank and the Triple Twin.
Individual Bullets fired from this tank are only 75% as durable as the ones spawned by Basic Tank, the Quad Tank however, shoots in four directions.
- Strong Against: Multiple Low-Level enemies, low health tanks.
- Weak Against: Focused Bullet spammers such as Twin, Destroyer branch, Ramming tanks, Snipers, Overseers/Overlords.
As the Quad Tank
- It may be better to stay as a Twin until the player is able to upgrade to an Octo Tank or an Auto 5 just like with the Triple Shot due to this tank’s numerous soft spots.
- Quad Tanks are decent at dealing with crowds of Polygons and great at dealing with many lower-leveled tanks. As a result, farming and multi-kills have never been simpler. As the Quad Tank has four Cannons, it can get two or more targets into range of its Cannons and spam Bullets. All the player needs to do is to turn Auto Fire and Auto Spin on, and watch the XP grow.
- The player should beware of fast rammers, as they can bump into the tank's weak points (between the cannons), and kill it. To counter, it is best to have high Reload, Bullet Speed, Penetration, and Damage and block its weak spots.
- Like the Octo Tank, it can spin to defend and block weak points. This is helpful against ramming builds, like the Booster, Tri-Angle, Destroyer, and Fighter.
- This tank is weak against most tanks with focused fire, such as the Twin and Triple Shot, not to mention the Sniper. It has many weak points compared with other classes of its tier, so it should try to do its best to protect itself, as it has four weak points where players can damage it from.
- It can easily defend itself in games by clicking "C" and "E" keys to simultaneously auto-fire and auto-spin. This will make the most of the player's tank, as opponents have difficulty time shooting in the gaps.
- The player should beware of Drone users as well, as the speed and damage of their Drones can mean that the Drones easily find and pierce the gaps between the player's Bullets.
- This tank is best used with a teammate; and though it has a good crowd-control ability, it is generally weak against focused fire tanks when left alone, so staying with the player's teammates is recommended.
Against the Quad Tank
- The Sniper tree (excluding the Trapper branch) are hard counters to the Quad Tank. They can easily pick it off due to the slow speed the Quad Tank has and its four gaps between its Cannons. This allows for an easy kill in all diagonal directions.
- Smasher and Tri-Angle branch tanks can engage the Quad Tank with Body Damage maxed out. They can charge at a Quad Tank while dodging its bullets and strike their body at a wide gap between the Cannons. The player should be careful when the Quad Tank has maxed out Bullet Damage, as they may get underestimated in several cases.
- The Sprayer is the most effective tank against the Quad Tank. The accurate Bullet spread may deal quick damage in the wide gaps between the Cannons of the Quad Tank. Due to the Sprayer's high RoF(Rate of Fire), it may also overwhelm the Quad Tank's RoF. In addition, accurate firing classes, such as the Streamliner or Triplet is also a good idea for this strategy.
- The Overlord can be effective against this tank, as it can guide its Drones between the gaps between the Cannons of the Quad Tank. The player can do this several times until the Quad Tank gets overwhelmed, making it an easy target.
- It used to be a Level 45 tank when there was a Tier 5 in the game.
- It is one of the first tanks to be added in Diep.io.
- Contrary to popular belief, the Quad Tank’s Bullets are slightly stronger than the Twin’s.