Feral Soul Stars.

Just another option to get Feral Soul Stars.

Make Feral Soul Stars crafted by using Perfect Tokens of Luck, Perfect Tokens of Best Luck, Iceshard Coin, Lucky Coin and increase the quantity of Feral Soul Star in Event Gold that instead of 25 per 1 Event gold make it 50 Feral Soul Star per 1 Event Gold. Another alternative by using Attendance Sheet since it says in the description that you can trade Attendance sheet for 100 Feral Soul Stars at the School Teacher.