Resembling a massive sphere, Megatanks are one of the most rarely seen and arguably the most dangerous of Xana's monsters. In fact, they have made the least appearances (Despite being the second monster introduced in the show, first being Kankrelats) of any normal monster and do more damage than any other monster. The weak points of the Megatank are its two Eyes, which are located opposite each other on a support ring inside its casing. The casing is able to resist any attack, even one from another Megatank (although it doesn't cancel out the force of the attack). It only opens this casing when preparing to fire, making it all the more dangerous to attack. Fake Eyes appear around its equatorial axis before it opens, as a sort of warning.
Megatanks move by rotating the two halves of their casings. This unique method of propulsion allows them to travel faster than anything on Lyoko, including the vehicles, but only marginally so. Megatanks lack the ability to slow themselves down quickly, which can lead to them falling into the digital sea through their own excess momentum. For this reason, they are rarely seen in the Mountain sector. Megatanks have some limited mobility beyond rolling their cases; if knocked on their side, they can realign themselves before rolling again. Their weight and speed also enables them to flatten and devirtualize the warriors if given the chance. The Megatank is the only monster on lyoko able to block all of the Lyoko Warrior's weapons, as long as its shell it closed, it can also withstand Aelita's energy field.
The Megatank's only weapon is its massive elliptical laser, which is charged and fired from the support ring inside its casing. This circular setup allows it to fire both behind and ahead of itself simultaneously. Alternatively, the Megatank can rotate on its side and fire sideways, creating a nearly unavoidable attack if the lyoko warriors are on ground. The Megatank's laser has one of the longest ranges of any weapon, and fires as a solid pulse instead of a short burst. However, due to this setup, the weapon must reach its destination and retreat before the Megatank can fire again. Though the Megatank can fire rapidly if need be, it needs to pause every so often to recharge its weapon. Megatanks normally fire their attack while stationary, though they can fire it while running, albeit with greater difficulty. The Megatank's laser only did fifty points of damage per hit at first, but started to do one hundred points of damage per hit after the episode "Code: Earth". The official site has both damage totals listed.
Before the episode "Code: Earth", the Megatank's laser was usually impeded when it struck someone or something, allowing the others to shield Aelita with their body, but with the damage increase, they can now shoot straight through any of the heroes, making the previous strategy of self-sacrifice useless. In addition to that, the Megatanks became the only monsters with a weapon capable of altering the landscape of Lyoko. It can cleanly slice through most objects on Lyoko, though a sufficiently thick object will stop the attack. Strangely, the Megatank doesn't damage the ground it is on when firing its laser. Aelita and Ulrich have weapons capable of blocking the Megatank's laser, but the force behind the blast prevents them from doing so for long. Ulrich's solid weapon is less effective than Aelita's energy-based one, so he has more trouble stopping the attack. It can actually shatter his sword if given enough time. Aelita, however, can shatter the Megatank's laser itself with two energy fields; the attack scatters the laser into glass-like pieces of energy in every direction that disappear after a short period.
The Megatank is also the only monster powerful enough to damage a tower, other than the specially-created Kolossus. Megatanks have attacked towers twice so far. The first time was in the first season episode "Code: Earth", in order to prevent Aelita from reaching the real world. The second time was in the second season episode "Contact", in order to shut down a tower being used by Franz Hopper. When they cause enough damage, the tower that they're attacking shuts down completely. They failed the first time, but succeeded the second.
Megatanks usually travel alone, but will travel in groups of two or three if Xana is desperate. Their strategy is fairly simple, but overwhelmingly effective in most cases. They keep their outer shells closed until they're ready to attack, then close them right after doing so. This makes damaging them quite difficult. Their speed also allows them to keep in range of their targets easily, preventing any escape. In the Mountain sector, they can use their massive laser blast to blockade smaller paths. Since their attack and invulnerable shell prevents effective close-range combat, Odd has the best record against the Megatanks. At the end of one episode Jeremy supposedly went into Lyoko for the first time(however it was never shown), and had just come out of the materilaztion room. During Ulrich joked about how fast a Megatank finished him. That was the only known time he went into Lyoko to battle, after which he never entered again. It was never revealed Jeremie would look like in Lyoko though Odd and Ulrich says that he looks ridiculous.