Everyone here was a veteran at games; they had a good understanding towards control effects. Among all control effects, stun and knock-up were definitely the strongest.
Rooting could only restrain a target's movement. On the other hand, not only could stunning cause one to be rooted, it would also disrupt a target's skill.
Since Dark Barrier was able to root the two people in the first row, this proved that this BOSS's control judgement wasn't very strong. After Dark Barrier ended, the two continued to move forward, showing that the BOSS's skill was still functioning.
Thus, stunning was needed to disrupt the BOSS's skill.
At this point, Fearless and Vainglory had already climbed up onto the BOSS's bed. The Bloody Countess smiled sweetly, revealing her sharp teeth. She extended her hand and grabbed towards the two of them.