I haven't played in a while and I was thinking of getting back in.  Not sure how well this deck's gonna do and I'd rather have it fail here than go through the expense of building it and have it fail there.  Constructive criticism welcomed and greatly valued.  Thanks!

This will sound weird, and some will take my suggestion as insulting - or as a point of weakness on my part. That said, if you got'em, i would have at least 3 copies of Path of the Master. Not for the damage pump aspect, as this deck has damage pump for days. Rather, i would have it in here for another way to draw cards.

Strength Within, Defeated the Rifle, and Battle-Tested all have symbol specific abilities that allow you to draw cards. Also, please remember that you can pay the cost for an ability even if the effect won't resolve. So, on your opponent's turn, you COULD play Strength Within or Defeated to draw a card; particularly helpful if you've exhausted your hand, or are forced to pitch cards.

You should ditch the Ymirfang for Path Of The Masterlike RockStar said, and then ditch the Reaver's Axe for a couple more foundations. With the amount of actions, attacks and assets you are running at the moment, you will have many sub-par opening hands. But that's just me.

I'm a particular fan of Mitsu at the moment, so i will write again...

Please consider the following cards for your deck:

Brooding

Ruthless

Hope for One's People

All of the cards are 1-difficulty or less, so they're fantastic for spamming. They are also very functional for a Mitsu build, imo, because you don't care if you blow them up for Mitsu's FirstF or not. It's like, if you have them available for the card effects, great. If not, no worries...you probably blew them up for Mitsu's even better effect, y'know.

As it stands now, my biggest critique of your deck is that it's supposed to be fast. This means your T1 foundation drop is extremely important; you must play as many foundations as possible, so that by T2, you're ready to smash face. As it stands now, i think your deck plays too slow.
 

 Thank you for the help.  I took your suggestions and added Path in place of Ymirfang and replaced Reaver's Axe with Ruthless.  Not sure where to fit the other two sets of foundations in though.  Any ideas?