Angel Stones are spells, summoned creatures, and passive skills. Level your Angel Stones each time your character levels. They can level up to your character's current level.

Boss battles are usually easier if you still have your summons. Choose the proper skill that is relevant to the Boss you are facing. For more difficult Bosses, learn their attack patterns and retreat when necessary before using an Angel Stone to counter attack.

Consider choosing either the melee fighter or mage. The ranged hero seems weaker than the others.

Do not use the auto walk feature. When auto walking, you cannot issue specific orders to a character. It is better to have complete control to be able to switch attacking position or to retreat.

Use your special skills at the best time to get the most damage. For example, wait until there are many enemies nearby before using anything that has an area of effect.