Treble Boost is a utility weapon exclusive to Bass that allows him to fly freely and shoot three shots at once in a spread shot when he fuses with his robotic companion Treble. This fusion first appeared in Mega Man 8, but was made usable by the player in Mega Man & Bass and Mega Man 10. In Mega Man Maker, it replaces the Rush Coil/Proto Coil, Rush Jet/Proto Jet, Power Adaptor, Jet Adaptor, and Super Adaptor.
To activate it, the player must press fire and walk into Treble while he appears. When summoned, Treble will be growling for a while before disappearing if Bass does not fuse with him, similar to Rush's behavior when he is summoned for his Coil and Jet utilities. The combination remains until Bass changes to another weapon or the energy runs out. When the weapon loses all energy, Bass goes to his normal stance.
During the Treble Boost, the shots are distinct from Bass' normal buster shots. They can pass through walls and they do 1 point of damage, but with the drawbacks of not being able to fire rapidly and needing to wait the three shots to despawn before shooting again. Outside of the fusion, Bass will fire shots with the same characteristics of Mega Man's uncharged Mega Buster shots.
The concept of stronger shots and its base mechanics come from Mega Man & Bass, while the fusion with Treble was taken from Mega Man 10.
When destroying Weapon Blocks, they can only be destroyed by a specific version of the Treble Boost. This has to do with its substitute for the utilities of other characters, who need the determined utility weapon to destroy the Block. The Rush Coil and Jet still have their own ID.
- When first introduced, there was a bug that occurred where if Bass picked up a Weapon Capsule while transformed where if he did not touch the ground when picking it up, he would appear to turn back to normal with the weapon equipped but would maintain his flying ability and inability to be staggered, allowing him to fly indefinitely with the new weapon equip. It was later patched in a following update. A similar glitch to the previous can however still be performed if the Player Character performs a series of actions that allow them to trick the game into letting Bass fuse with Treble while equipped with another weapon.
- If Treble is summoned and lands just as a Yoku Block appears one block of space above him, he might not complete his teleport animation and will be stuck in the last frame, causing him to look like a massive purple and white blob. He can however still be merged with like normal if walked into. He does not however seem to teleport away if left alone for a while as the game may still think he is trying to teleport in.