Yulster was momentarily stunned, but he soon understood.
This was the protection of the Blood Contract!
He was already the Blood Favored of the True Ancestor, under the protection of Thorns and Roses, no one could forcibly control him using Spirit Magic!
Not to mention Duke Yoroc who was also a Descendant of Blood, his "Blood Law Truth Technique" didn't even send out an alarm before it was devoured by the protective power of the thorny rose!
Realizing this, Yulster was both shocked and delighted.
He was shocked by how far beyond his expectations the True Ancestor's suppression of the Bloodline was, and delighted that his hidden secrets were finally safe from being exposed.
Honestly, he had already resigned himself to his fate, so he wasn't very afraid of how Duke Yoroc might respond upon discovering the truth.
What he feared was if he accidentally sabotaged the True Ancestor's plans and incurred His severe punishment!