First, Normal Summon "Fabled Raven." Then, add "Fabled Krus" to your hand with the effect of "Fabled Grimro."

Now, activate the effect of "Fabled Raven" and discard "Fabled Krus" to activate its effect.

When you do this, you will trigger the effect of "Fabled Krus" and this will let you Special Summon "Fabled Grimro" from the Graveyard.

"Fabled Raven" will become Level 3 with its own effect, meaning you'll be able to Synchro Summon a Level 7 monster.