Play in Endless mode to earn character disks. The only other way of obtaining them are by opening chests and redeeming login bonuses. Endless mode becomes available after level 10 and features deadly traps and dangerous enemies. The enemies and traps scale in difficulty the further you progress. The rewards will also increase in value the longer you last.
Scoring
A total of three stars can be earned per level. The first star is awarded after completing the level. The second star is awarded after all enemies in the level are defeated. The last star is awarded by completing the level under a specific time limit. Complete a level without taking any damage to receive a no damage bonus which adds 100% more points to your final score.
Team bonus
Unlock as many new fighters as possible. Each fighter has a passive "team bonus" that is active regardless of whether you are playing as them. These will give you extra health, attack, defense, and similar bonuses.
Weapons
Each weapon category does a specific type of damage. For example, swords deal slashing damage and knuckles result in crushing damage. Use weapons that are effective against the enemies that you will encounter. Use the preview of a level to determine what type of damage an enemy is vulnerable to.