Monado Buster (モナドバスター, Monado Buster), often shortened to just Buster (バスター, Buster), is one of Shulk's Monado Arts in Xenoblade Chronicles and Future Connected. It involves Shulk powering up the Monado for a giant overhead slash, hitting all enemies in a line and dealing double damage to Mechon. The bonus effect does not trigger against Face Mechon, even if they are toppled, if the Monado cannot harm them normally.
Monado Buster is Shulk's most powerful Art by a decent margin, even before the damage bonus against Mechon. However, because the damage it deals makes Shulk likely to draw a large amount of aggro from any enemies he hits, and also because it uses up his entire talent gauge, Buster can be risky to go for unless it's used as a finishing move. It is also among the most expensive Arts to upgrade, though even without upgrades it's quite powerful.
In the Super Smash Bros. series, Shulk uses Monado Buster as one of the options of his neutral special move, Monado Arts. While Buster is active, Shulk deals significantly more damage, but pitiful knockback, and receives more damage himself. These effects are more akin to Monado Enchant.