There are different levels of monsters on the world map. You have to beat them gradually, starting from level 1 up to the highest level. For example, you can only attack a monster at level 2 if you defeat a level 1 monster.
 Defeating a new level of monsters for the first time will give you a first-break reward and booty. Repeating the challenge of defeating monsters will give you a chance to get various precious props, including hero shards and crystals.
 Attacking the monsters might cause some injuries to your soldiers. They will automatically go to your hospital inside the castle. If the hospital is full, they will be sent directly to the alliance hospital if only you join an alliance and the hospital has been built.