Capítulo 89: Part 1: Got Beaten

So, Mr. James is quite sure about it. If Zack maintained a certain distance from the Black Tree Monster. Then, he will be able to cover his back.

Meanwhile,

The Black Tree sensed certain prey is standing near. It decided to kill the prey and suck out its blood using the root. The Black Tree Monster consumes its food nutrients by this indirect method.

It doesn't have another killing method. Being, a tree species, it got a long life span. It consumes food nutrients from this black soil using its root.

It is a direct method. And it's the proper natural way. But, nutrients are present in this black soil. Won't be enough for its successful evolution. So, Ever since the black tree got leveled up to Class 2. Its intelligence has grown with evolution. 

Then the black tree started to find a way to evolve faster. Then, one day it comes up with the method to kill other monsters and consume their blood.