The Slender Reimagined Mod for Minecraft, developed by "iChun", is a mod that enables the spawn of eight pages in locations up to five hundred blocks away (underground is considered fair play, in this case) from the spawn point, randomly. SlenderMan is always lurking nearby, regardless of how simplistic this mod makes things sound.
To banish him, the player must collect all eight scattered pages.
SlenderMan is observing each movement the player makes carefully, but as long as the player does not provoke him, SlenderMan will not attack. He will also refrain from bringing harm upon creative and/or sleeping players.
However, he does mind when the player gathers pages (which may result in injuries bestowed by SlenderMan) and the more in the possession of the player, the more aggressive SlenderMan becomes.
This mod brings a real challenge to the table and is very useful for those players who believe they have capabilities to trick SlenderMan. They are reminded that he is very observant and relentlessly watching.