I'd say mono fire or mono dark. Go ahead and search for a deck like those.
If you'd rather have an almost 100% win percentage, go with fire/light with time mark (there's a topic here). It's not necessarily speed, but it isn't rainbow slow either. Once you upgrade the sundials go ahead and drop the light pillars for a light mark.
Here's a link to the fire deck PuppyChow is referencing:
http://elementstheforum.smfforfree3.com/index.php/topic,791.0.html (
http://elementstheforum.smfforfree3.com/index.php/topic,791.0.html)
I'm still new to the game, but this is what I've been using and it wins a large percentage of the time. I don't have any of the cards upgraded yet, and I only recently obtained a Fahrenheit. I was using a Short Sword in its place and it still won most of the time, though it's definitely better now. It's not super fast, but it's reliable and will only get better and faster as you upgrade cards. I run with the 2 Deflagrations mentioned at the above link. I prefer them to Golden Hourglasses (at least for now).
There are a few decks that give me trouble, but keep in mind I just got Fahrenheit, so it may help take care of some of these difficulties by speeding up the damage output significantly.
Poison is hard to beat because you're waiting to get your Fire Quantum built up enough to kill your opponent all at once using Firebolts. So while you're stalling with Sundials, your health is draining away faster and faster.
Earthquake/Pulverizer decks are very hard to beat as well because you keep losing your Fire Pillars and thus can't build up enough Quantum to make your Firebolts do enough damage before you run out of cards and you lose your Sundials, keeping you from being able to stall as well.
And then there's Jade Shield and Reflective Shield. If either of those cards comes out, it's game over unless you have Farenheit and can keep it in play. If not, just go to Menu and start a new game - save yourself the slow death you will certainly suffer otherwise.
Good luck!
Kelson
