First off, i should point out that skillgannons mono dark deck will work better until you can afford to upgrade 6 ash eaters. This mono fire deck kills faster once you can afford it though, even faster than his fully upgraded deck. Once my entire fire deck is upgraded it is just ridiculously fast.
I design my AI3 grind decks to be so simple you could simply click all the cards without even looking, then press space, and you will still win very fast. I watch tv and do other things while grinding so i dont pay attention at all. You should change this if you plan on paying attention while playing.
Here it is fully upgraded, but like i said, all you need upgraded is ash eaters and it will still do very well.
Click deck image for interactive version
Before i tested the deck i thought i would get smashed by maxwell and otyog decks like the mono black did without drain lifes, but suprisingly i still beat them most of the time, only 2 losses out of 50 games in 1 hour. The damage just adds up so quick, that even if my crimson dragons only last 1 turn before being eaten i still win. the ash eater damage adds up alot more than i thought it would as well.
EDIT: Before people start complaining about no masteries, You will learn that in AI3 grinding you will get more $$$ from the slots than you ever would from masteries. You can play 4-5 games with a speed deck in the amount of time it takes to play 1 game with a mastery. Speed is better, and there is no arguing that.