Serenade

 is a power skill which summons a friendly flying sword. It is exclusively obtained from the Fatal Falls DLC.

As Melee Weapon

 * Base DPS: 53 (159)
 * Base Combo Damage: 75 (225)
 * First Hit: 20 (60)
 * Second Hit: 25 (75)
 * Third Hit: 30 (90)

As an Item

 * Base DPS: 30 (360)
 * Base Combo Damage: 54 (648)
 * First Hit: 22 (264)
 * Second Hit: 32 (384)

Location
In the Fractured Shrines there is an island that can be reached by platforming over invisible platforms; the rain splashes reveal their location. After that, there is a small gauntlet of traps that leads to a temple blocked by three layers of breakable floor thus requiring the to get inside.

In the building, there is a Stone Warden guarding a door which leads to a unique treasure room with a vault inside. Opening the vault will free Serenade, forcing it onto a skill slot. The blueprint itself goes in your inventory and still needs to be delivered to the Collector.

bugs
In the (Current?) version of the game spamming the sernade spawn and switch button allows you to end the cooldown of your second ability allowing you to spam it