Walter is a "nothingness" destiny character with imaginary attributes in Honkai Star Railroad. He is an auxiliary character with deceleration and control as the core mechanism. He has a very good performance in the push-stream lineup. So I will tell you what materials are needed to upgrade Walter.
Character advancement materials
Level 20 and 30 promotion materials
Iron Guard Buckle
40.50 level promotion materials
Iron Guard emblem
Gold Jewelry of Shadows of the Past
Level 60 and 70 promotion materials
Order of the Iron Guard
Gold Jewelry of Shadows of the Past
