The king summons you to defeat the monster and his minions and to capture his castle. Kill more than one monster simultaneously and earn a 'chain bonus'. The more enemies you kill simultaneously, the higher your bonus will be!
If you use WASD to move around, then press J to attack and K and L to use skills.
If you use the arrow keys, then press Z to attack and X and C to use skills.
If you want to roll, press a direction key (WASD / arrow keys) twice.