It's easy to get lost in the mediocre and unnecessary sea of mashups on the internet; however, every now and then you find a pearl that's worth your time.
Normally, my favorite mashups are those that draw together totally incongruous songs, stuff that you never expected to go together. See Girl Talk's incredible blend of Biggie, Pharcyde and Elton John (starts @ 1:25)
However, sometimes a mashup that pairs two similar songs can be just as good, as long as something is added to the material in the way that the producer splices it all together. Nate Belasco's combination of Kanye's "Black Skinhead" and Tame Imapala's "Elephant" accomplishes just that.
Now say what you will about Yeezus--creative riffs devoid of any lyrical content--but this song is a banger.
The interchangeability of the guitar parts is perhaps my favorite aspect. Check it out.
Note: There's a free download via the "buy" link in the soundcloud player.