The Proto Buster is Proto Man's signature weapon, being usable in Mega Man 9 and Mega Man 10. It is also usable in Mega Man Powered Up in the form of the Proto Strike. It is featured in Mega Man Maker as of 1.3.0.
It allows the user to shoot up to two small energy shots at a time that can pass through solid tiles and objects. These shots are fired slightly lower than that of the Mega Buster, and shots can be charged by holding the attack key. A half-charged shot deals the same amount of damage than an uncharged one, but is slightly larger. A fully-charged shot deals more damage, and is visually identical to the Mega Buster's MM4 shot type. They will continue on even after destroying an enemy or object. Only one charged shot can be onscreen at a time.
The Proto Strike is an optional setting for the Proto Buster than can be enabled or disabled in the Level Settings of the Level Builder. When active, the user can instantly fire charged shots, with an onscreen limit of two. These shots are visually identical to the Mega Buster's MM6 shot type. Like normal charged shots, they will not despawn upon destroying an enemy or object.