EpicDuel is fairly simple. It revolves around killing lots of monsters (grinding) to higher levels and allying with other players as part of factions. All factions fall under one of two groups: Legion or Exile.
This walkthrough points you in the direction of the NPCs to fight as you level up, and how to better your stats.
Starting out: Central Station
When you first begin the game you will be on the west side of Central Station. Here you will find the first NPC to fight: a Light City Guard (level 1). Challenge him over and over until you level up.
After reaching level 2, you can continue to grind on the same NPC, or attempt Junker one screen to the left. Alternatively, you can go to Fortune City, enter into the inner wall, then walk all the way to the right and find a Light City Guard (level 3).