Immediately, the whole place was covered by a black liquid. The Monster uses the shadow element to cover that whole area so that he can kill that invisible enemy.
Fortunately, Sam is not affected by the shadow around him. The Monster is unable to prevent him from moving or anything like that.
You can already see the monster was also injured. This is the reason why even though he covered the whole area with shadow elements he maintained the distance.
From every direction, he created those shadow balls and attacked everywhere. He wanted to know the exact location of Sam.
In this situation, Sam can feel the restriction force around that area. Even though the Boss monster did not use the power of domain by using the shadow element he can still restrict the space around him.
Sam uses the bloodline pressure that immediately affects that monster. He also uses the energy booster and in the next second attacks the Monster using the light element.