Niroc

i have a question,i watched a ftb lite lets play some weeks ago and there was a mod which told you how much blocks you are away from someone and the player was like a walking beacon,does anyone know what that mod is called?

Hello, I started a server with my friends and we do wanna have fight situations,but only if you've found the base of someone. But we didnt make a limit for building,so the problem is half of the people are building in the underground so you cant find them and thats hella annoying,so is there a way to find/detect players or their bases?