Since my last review was... short, I decided to post another one today. You're welcome.
I used to run a Madness deck, and I had 4 copies of this card. Of course, there aren't that many cards in red or green that have Madness. However, discarding a Fiery Temper and turning it into 5 damage for 3 or even chucking a Basking Rootwalla with a cardless Shock. Now, this is a little pricey since it costs 2 for that Shock, but its 2 colourless, and in a dual-colour deck that's pretty nice, but the randomness of the discard is a little annoying and it might result in you discarding a land or something without Madness. I'll admit it, my deck wasn't the greatest...
Pros: Turns cards into colourless Shocks
Cons: The Shocks cost 2, discard is random