Metronome

Metronome is a passive item.

Effects

 * Grants a +2% damage bonus for each enemy killed. The effect maxes out at +150% weapon damage (75 consecutive kills).
 * The bonus is reset if the player takes damage, changes guns, or drops their gun.
 * Picking up a new gun does not reset the bonus, effectively transferring the bonus to the new gun.
 * After each kill a tone will play and a small note will appear above the player's head. As the damage bonus increases the tone will become higher pitched and the note will change color.  The note is red when the bonus is maxed out.

Synergies

 * If the player has Drum Clip, the damage increase is changed to +4% damage per kill instead of +2%, and maxes out at +250% damage instead of +150%. The note at max level becomes silver. Picking up Drum Clip after Metronome resets the damage bonus.
 * Doubles the spread of the Face Melter and Gunzheng.
 * If the player also has Really Special Lute, the gun's spread is drastically decreased.

Trivia

 * This is a reference to the item of the same name from the Pokémon series, which works similarly, gradually increasing the damage of a move if used several times in a row.