To awaken a unit to its 7★ form, you need two of the same unit. One unit (base unit) must be at max level (100). The other unit can be in 5★ or 6★ form.
To awaken your base unit to its 7★ form, you will need a material called a 'prism.' To obtain a prism, simply convert your 5★ or 6★ duplicate unit.
To awaken your base unit to its 7★ form, you will need a material called a 'prism.' To obtain a prism, simply convert your 5★ or 6★ duplicate unit.