Dragunity/ Assault Mode was one of my favourite casual decks from the September banlist, which I've decided to revive for the current format. The premise of the deck is fairly simple - exploit Dragunity's inherent ability to pump out level 8 Synchros to control the game and get out an early Assault Mode. While I used to run a turbo build with triple Upstart Goblin and Cards of Consonance, the deck tended to either win or lose big, wheras the current build is far more consistent.
Easily the most powerful of the OCG exclusives, Crimson Blader has enormous synergy with Assault Mode. In a deck designed to pump out level 8 Synchros, Crimson Blader can normally be made the turn after a successful Stardust summon. Assault Mode can use its negation to shield Crimson Blader from any destructive effects, and in return, Crimson Blader can soft-lock the opponent out of any boss monsters that would run over Assault Mode in battle for a minimum of a turn. While it was more effective in the previous format, before the XYZ monsters that could bypass Crimson Blader became big, but Blader is still extremely effective in any Synchro-based matchup.
Daigusto Emeral is the other preference card of the deck - as ****ault Mode is completely dead in the hand, I tend to discard them using Dragon Ravine, then use Daigusto as a second Pot of Avarice, recycling him along with any Duxes or Synchros in my grave. However, the only way to consistently play him is via Zephyros, so I would be open to reccomendations as to whether or not to keep him. Quill Feather of Gulldos is another option to recycle Assault Mode and Dux, but I found the card to be dead far more often than I benefitted from it, and the deck is still capable of playing as a standard Dragunity deck should both the Assault Modes be stuck in the grave or RFP.