The X-Buster (エックスバスター,Ekkusu Basutā) is Mega Man X's primary weapon in all games from the Mega Man X series. It is a Mega Buster Mark 17 created by Dr. Light alongside X. X can transform either of his arms into a powerful buster to shoot bullets of compressed solar energy, and has an energy amplifier that allows it to be charged up and release a more powerful shot.
The X-Buster also has a Variable Weapon System that allows X to use the Special Weapons of Reploids defeated by him, and it can also be powered up with different Armor Parts and Power-Up Parts. In The Day of Sigma, it's shown that X can detach his buster.
In Mega Man X: Command Mission, the X Buster was redesigned alongside X's New Armor, and it is his starting weapon.
X can find better versions of the X Buster during the game, the X Buster MKII and X Buster MKIII. X can also equip different types of busters. Its attack is named Buster Shot. His Action Trigger is a Charge Shot.
The Arm Parts obtained by X allows him to charge his buster further to use more powerful attacks. Excluding the Gaea Armor and Shadow Armor, all Arm Parts allow X to charge Special Weapons.
|First Armor||Spiral Crush Buster|
|X can charge his buster further, the third charge shot firing three trails of five spiraling shots.|
|Exclusive to the PSP remake of Mega Man X1, after adquiring the Buster Upgrade from Zero if the player didn't adquire it from the Capsule, X can fire a powerful red shot, identical to Zero's.|
|Second Armor||Double Charge Shot|
|X can charge his buster further. The third and fourth charge shots are identical to the first and second, but after the attack X has energy stored to fire another shot with two trails of four shots spinning around it.|
|Third Armor||Cross Charge Shot|
|X can charge up to four charge levels. At the fourth, X can fire out a Cross Charge Shot by shooting both busters in each arm in rapid succession. When the Armor is fully assembled, X uses half the weapon energy for his Special Weapons. With the Arm Chip, X will be able to use unlimited charge shots as long as the Hyper Charge has weapon energy.
After adquiring Zero's Z-Saber, X will be able to charge up to five charge levels, shooting a saber beam.
|Fourth Armor||Stock Charge Shot|
|One of the two charge shots that X can choose in Mega Man X4. X can store up to four Charged Shots and fire them in a burst or separately.|
|Plasma Charge Shot|
|One of the two charge shots that X can choose in Mega Man X4, it leaves multiple Plasma balls behind after hitting enemies.
In Mega Man X5, this is the armor's default charge shot, however, it can only leave one Plasma ball behind.
|Ultimate Armor||Used from Mega Man X4 to Mega Man X6, and Mega Man X8.|
|Falcon Armor||Spear Charge Shot|
|A shot that can pierce through any obstacle in Mega Man X5.
In Mega Man X6 it lost its piercing property, however, it allows X to charge the Special Weapons.
|Gaea Armor||Gaea Shot|
|A powerful buster variant turning the series of shots into dark green and black hued energy blasts.
With one charge level, the buster is short ranged, but compensates in power and with a variety of effects: Destroys V marked Gaea Blocks and naturally carries Shot Eraser effect, allowing the neutralization of enemy shots.
|Blade Armor||Blade Shot|
|It functions similarly to the Plasma Charge shot, leaving one Plasma ball behind, however, X is also able to fire a Charged Saber attack by holding Up while firing the Charge Shot, which destroys projectiles.|
|Shadow Armor||Shadow Shot|
Crescent Moon Ring
|It functions similarly to the C-Shot special weapon, firing projectiles in random directions.
Similarly to the Gaea Armor, it only has one charge level. Firing a Saber Swing that creates a Crescent Moon, dealing multiple hits to enemies.
|Glide Armor||Glide Shot|
|It adds three homing bullets to the charged shot.|
|Icarus Armor||Icarus Shot|
|X is able to fire LVL 1 Charged Shots as his regular shots, LVL 2 Charged Shots at his LVL 1 charge, LVL 3 Charged Shots at his LVL 2 charge and a Laser Beam at his LVL 3 charge.|
|Hermes Armor||Hermes Shot|
|X can fire 3 semi-charged shots in a spreading manner when the X-Buster is fully charged, with the added capability of breaking defences. Adds a fourth-level charged shot that shoots 5 semi-charged shots when X-Drive is in effect.|
The X-Buster is part of X's moveset.
Near the end of the story mode, Iron Man and Thanos work together to create a weapon that has the ability to channel the power of the four Infinity Stones the heroes had.
This weapon, dubbed the Infinity Buster by Iron Man, is given to X. X uses it to destroy Ultron Omega. The weapon was exceptionally powerful to such an extent that X had immense problems controlling said power even in his Ultimate form, experiencing violent convulsions while it was charging, thus requiring the heroes from both universes to lend X their energy via Doctor Strange and Morrigan as conduits to have X focus its charged energy long enough to obliterate Ultron Omega.
The X-Buster is near identical to the games, but originally it is only available in X's left arm. X can use Special Weapons by inserting chips from defeated enemy Reploids in his buster. During the battle against Sting Chameleon, his buster is severely damaged, but Armored Armadillo ordered a Metall C to repair it, disobeying Sigma's orders to have an honorable one-on-one combat against X.
Late in the story, X's buster is damaged again in the battle against Boomer Kuwanger in a tower, and becomes useless when he takes an energy cable from the tower and attaches it to his buster to fire a giant blast that destroyed Kuwanger and part of the tower. Without ways to attack, he's defenseless against Vile, but Zero gives his buster to X, allowing him to battle.
In the Rockman X2 manga, X gains the ability to use his buster with either arm, but he can use only one of them at a time.
However, when facing the three X-Hunters in their base, he uses both busters at the same time to defeat them.
The massive power of the buster is demonstrated again in the Rockman X4 manga, where X is able to mortally wound Repliforce guerrilla commander Web Spider with a single charged shot. The force of the blast resulted in Spider's head being dis-attached from his body, with him having to hold it in one hand before losing all strength and dying seconds later.