To gain experience faster in Metaphor: ReFantazio, follow these steps:

1. **Lower the Difficulty**
– **Easy Mode**: Playing on easy mode can significantly increase your experience gain. The bosses are easier, and you receive more experience overall, making it a nifty method to quickly rack up those numbers.

2. **Use Trance Crystals**
– **Trance Crystals**: These crystals spawn enemies endlessly until they are destroyed. You can find them in dungeons and use them to farm a lot of experience points. To maximize their effectiveness, avoid destroying the crystal and let it regenerate its health automatically.

3. **Complete Quests**
– **Unlocking Dungeons**: Completing quests unlocks more dungeons, which contain more enemies that you can kill and farm experience points from. This method is particularly useful for gaining access to new areas with higher levels of enemies.

4. **Battle Near Trance Crystals**
– **Endless Battling**: Fighting near Trance Crystals allows you to engage in endless battles without destroying the crystal itself. This method is efficient for maxing out your Archetypes quickly by constantly summoning enemies.

5. **Use Archetype Experience Items**
– **Hero’s Incense and Leaves of Light**: Using items like Hero’s Incense and gaining Hero’s Leaves of Light can give you a small boost in Archetype experience points. Hero’s Incense can be obtained from a character once you unlock Akademia, and Hero’s Leaves of Light are awarded every time you gain 1000 Archetype Experience points.

6. **Skill Inheritance and Synthesis Skills**
– **Archetype Skills**: Leveling up your Archetypes unlocks more skills, which can be inherited from other Archetypes based on the archetype you are currently assigned to. Using synthesis skills, which consume more turn icons, can also provide powerful abilities but should be used strategically.

By combining these methods, you can efficiently gain experience and level up your characters and Archetypes in Metaphor: ReFantazio.