I love this data pack but my dad blocked the website. I want to download it still so im posting it.
guide: (copy+pasted from the website)


Herobrine now has a chance to spawn randomly in your world. He will not attack or be hostile at all, unless looked at. If you look directly at his eyes he will do one of many things he can do including jumpscaring you, summoning lightning, summoning deadly zombies, effecting nearby players with blindness, and playing spooky sounds. He will also appear when mining, killing other animals, or sleeping in a bed and herobrine also spawn fire all over the world. Trees occasionally will be stripped of their leaves resulting in creepy forests with only stumps. Torches also occasionally turn into redstone torches and placed blocks have a chance to break a few seconds later. Lightning spawns even during clear weather and cave ambient noises now play on the surface as well. Herobrine can be spawned with 9 gold blocks, 1 netherrack, and 4 redstone torches and after an explosion will start following and attacking nearby players. Once killed his skull will remain on the ground which leads to a massive explosion when mined.

Requires Optifine!

Link: https://www.commandgeek.com/projects/herobrine