Changing vanilla mobs attitude towards a player

Hello!

I am new to MCreator and I was wondering how to get the event when an entity is trying to target a player and how to cancel it. I do this to modify hostile mobs aggressiveness depending on surrounding blocks in an area.

I also try to change vanilla mobs spawning rate depending on the same block existence in the area.

Of course this block comes from another mod so I also have to detect the presence of this mod to load my own mod and to use a block that is not vanilla.

I could take this second part from the other side and say that a block in particular is increasing hostile mobs by X% in an area arround them.

Thank you for your time!

-x