Within 10s after an Elemental Reaction is triggered, ATK is increased by 12/15/18/21/24% and Elemental Mastery is increased by 48/60/72/84/96.
In Game Description
A beacon that shows the direction of the wind. Not every idyll carried on the breeze remains a gentle thing…
How to Get Missive Windspear?
Missive Windspear can be obtained from Of Ballads and Brews event (Genshin Impact 3.1)
Weapon Upgrade Materials
Here’s all material used to upgrade Missive Windspear polearm: