Griefer

One who harasses other players in a game

A griefer or bad-faith player is a player in a multiplayer video game who deliberately and intentionally irritates, annoys or trolls other players within the game. Griefing is often accomplished by destroying things constructed by other players or stealing items. A griefer derives pleasure from the act of annoying other users, and as such, is a nuisance in online gaming communities.

This keyword could refer to multiple things. Here are some suggestions: