Needs another card’s effect to discard him for reviving.
Discard The Fabled Ganashia along with The Fabled Cerburrel with an effect like Fabled Raven. The Fabled Ganashia and The Fabled Cerburrel will then be revived and you can use them to Synchro into Fabled Ragin.
You can discard The Fabled Cerburrel and another card to revive Fabled Soulkius. The Fabled Cerburrel will then be revived with its own effect and you can use him along with Fabled Soulkius to summon Fabled Valkyrus.
You can use these effects to discard The Fabled Cerburrel to revive her with her own effect.