Weapon (great club), rare
Umberlee chose the Dance Macabre, a pirate ship that prowled the sword coast, as the raw material to create this vaunted great club. The storm the Bitch Queen raised shattered ship and crew until all that was left was a splinter of her mast. A splinter that help all of Umberlee's ferocity and furor, that yearned to break and shatter.
You have a +2 bonus to attack and damage rolls made with this magic weapon. Additionally, you may deal thunder damage instead of bludgeoning damage.
Storm Trooper You gain resistance to lightning and thunder damage while wielding Sunderstorm.
Seawolf (requires attunement) If you have the pirate background, you score a critical hit on a 19-20 while wielding Sunderstorm.