My prerelease was pretty awesome, I picked Rakdos, and didn't get a single Mythic (actually I got 2, both Selesyna, but all my G/W was shit), but pulled the Rakdos shockland and Dreadbore. Neither did I get a single cackler, only one Hellhole Flailer, so what saved my ass? 4 Shred Freaks, always watch out for those guys, as they were the only reason I went 5-1 and got 3rd place.
Didn't really stay too long into the second prerelease as I was tired though.
On a side note, Rakdos is without a doubt the most powerful in limited, where I was at all of the top 3 were Rakdos, I knew 1 Azorius was somewhere in the top 8 and that 4th place was Selesyna though.