Prerelease didn't go too well for me, and I went 3-3. I ran a black-red madness deck, but I lost my first three matches, two of them 0-2. After that point, I reexamined by deck and realized that I was half-aggro, half-control, and I made some small adjustments to favor control. If I was going to go aggro, then black-green would have been stronger, due to the number of two-drops, but I wanted to actually play with my madness spells, and black-red had all the discard and madness cards. I pulled Sorin and Startled Awake as my mythics, but neither white nor blue were that good otherwise.
I can't tell if my adjustments to my deck actually helped, since my last three opponents were all beginner players who weren't very good. That also makes it hard for me to evaluate how well cards did and such. Still, I did use the madness cost of many cards successfully, including From Under the Floorboards.