Young Thug performs tonight at Roseland; more details here.

In the mid-to-late '00s, Lil Wayne was the most creative and prolific popular force in rap. He did little, it seemed, aside from take drugs and record.

That double cup, since discarded, has been picked up by Atlanta rapper Young Thug. And where Weezy offered unmatched lyrical flights of fancy, untethered metaphors, and slippery turns of phrase, Thug's innovations are sonic and melodic. He's far out, so comfortable in deep space that it's often difficult to tell what the 23-year-old ATLien is saying—if he's even using words at all.

Sometimes that's because Thug is buried in vocal effects. Other times it's because he's using his mouth to make sounds. He mumbles, mutters, squawks, and croaks. He warbles around notes and never finds them. And, of course, he raps too—as the adage goes, you've got to know the rules before you can break them.

I played Young Thug for a friend, a fan of hip-hop and deep free-jazz exploration. I cued up "Lifestyle," a leftfield hit. Words are mangled, dripping into gibberish, indiscernible syllables pushed and pulled. "What is this, dude?" my friend shot back, scratching his head.

Love Mercury Music Coverage?

Indeed, Thugga's is an emergent vocabulary, and it may take a little getting used to. As such, I've created a playlist in service of giving him a more proper introduction, and also to help cut through the clutter—after releasing some six mixtapes in the past year alone, there's plenty of gristle. And while this primer is neither comprehensive nor an absolute "best of," it should show some range, from the croaks of conspicuous consumption to the croons of heartbreak. Indeed, Young Thug is a rounded, feeling human being, despite what all the alien utterances might lead you to believe.