The Sibyl Sisters Series - Freya ... worth your time?

If I were to summarize it in one word, No.

It's not worth to spend your energy on Freya, the first unit under the Sibyl Sisters Series.

Freya is not a top tier unit. Her stats are at best mediocre and will not be in your first team for long. She is more like a collector's item.

However, I would still recommend that you try to clear the level four dungeon for the gem! =)

I was able to clear it today with my almost dark mono team and managed to capture Freya after 2 tries. ^^

To manage the level 4 dungeon, I would recommend a team of 5* units (level max)

I hadn't try to clear the dungeon with a rainbow team but any mono team less earth and dark elements should be able to clear the level 4 dungeon. 

I would also recommend bringing along Ores and seal as you will be needing the boost in attack and defense in your battle against Freya. 

You need a healer too as despite her weak stats, she hits like a truck. =x

If you are in need of paladin or fate stone, this is actually a good chance to stock up on them in this dungeon. Additionally, there is a small chance that you can capture Fire god and burst frog too!

So summoners! Good luck on clearing this dungeon and capturing Freya! 

Do share with me the team setup, strategies you employed to clear the dungeon. =)