Savage Mode is something of a minor masterpiece in sound design. For as merciless as 21 Savage’s writing can be, the album borders on ambient, lulling the listener into a false sense of security time and time again. “Mad High” is brilliant top to bottom, but the piano in the last act elevates it to a new level. Metro made his name with raucous, unhinged beats by the pound, but he’s beginning to show just how innovative he can be given some constraints, even when—or especially when—those constraints are self-imposed.