How do i make a horror mod i want to make The broken script Like Mod

Well I wanted to make a horror mod but I suck at Mcreator i used to use Mcreator 1.14.4 but ngl that's OUT DATED  So i decied to make this forum

I will be using 1.16.5 Sence i can use that version on my potato pc its a Dell optiplex 790 intel i3k so i all ready made some The broken script level thing monster

yeah his name is NULL404 and if he touches you he will insta kill you and Damage all of your items by 20 SO thats a good start allready

So Can ya help me also I want to add some OS things in there like crashing the game putting FILES on ur desktop etc