Hi Guys I'm EkulRenllaw here, and I'm sharing my Herobrine sighting. I started up a new survival world in 1.10, and wanted to see what was new. My world started out in a large forest, and I was walking around, pretending to be stranded in the wilderness away from any other people. So I continued along, and i noticed a group of oak trees that had 2-4 blocks cut out in the middle. I thought it could be the world generator bugging out, so i let it go and continued. I managed to travel to plains, and saw a sign in the middle of the plains biome, surrounded by redstone torches. I also realized scattered across the plains were oak trees with no leaves. I thought maybe the developers had added some sort of secret biome as a joke, so I walked to see what the sign said. It read: "Ouy Ot Emoc Lliw Htead" I realized flipped this read "Death will come to you". I was creeped out. And i started away from the sign. However, I looked behind me and saw him. He didn't move, and I was so crazed and scared, I quit the world and deleted it.
I don't know if Mojang added a prank biome and a herobrine mob, but no developer seems to ever want to add Herobrine. But he is still there, watching you.