Initially I was incredibly wary of Heroes of War (HoW).  I made a decision after I left Supercell that I would never work on a clone of Clash of Clans.  HoW featured every single thing I didn't want to work on, that was until the concept artist (an avid heavy metal fan) showed me his ideas based on heavy metal album art from the late 70's to the mid 80's.  We made an agreement then that all of our artwork and advertisements should feel like we pulled them off of the side of a van.