DarkJello wrote:
My thoughts on the aforementioned card:
Defeating mist is tough enough for mere mortals, but conquering "Themist" is a ludicrous challenge!  Only angels that don't believe in god and trolls that live in presumably luxurious caves need apply.  All others, step to the curb like a bad dog please...    
  
 DarkJello   

The only way to defeat themist is experience.  Heck, I've lost to him 10 billion times, but I've seen him lose ( and I bet 1 power that he would win 

). 
Basically, your best bet is to either lockdown his strategy or prepare a deck that counters everything he's got.  It's not impossible, but you can try.