You can put in the game the option of someone creating a guild, so everyone has his own guild or being member of a guild, also put guild leagues with tiers and bonuses from its tier. Now for the gameplay you can put the option of a guild attacking to another one and let 12 hours players give their participation to the attack or the defense, when the time for the battle has come every player will pick a dragon to fight for him and his guild, but the battle will be automatic none of the players can control his dragon and pick the right or the wrong move, it will be like the battles with your friends when they attack to you, you don't control your dragons move and the computer will pick the right move that believes it's the best for the battle... πŸ˜‰thanks for your time