There are two ways of joining this covenant: Defeat either the Royal Rat Vanguard in the Grave of Saints area, or the Royal Rat Authority in Doors of Pharros. After defeating either boss, you will be rewarded with the boss soul, along with a Rat Tail. Directly after each of the boss rooms, is a room where the Rat King can be located. Talking to him with a Rat Tail in your inventory is required for the Rat King to initiate the player into the covenant.
The purpose of the Rat King covenant is to defend the Grave of Saints and the Doors of Pharros. As a result, enemies in the area become non-hostile toward the member, and instead will act as friendlies which will assist the member. While wearing the Crest of the Rat ring, other players who are in the Grave will be pulled into the player's world as a gray phantom. Each defeat of a gray phantom yields a Rat Tail and a Pharros' Lockstone. Gray phantoms can escape the Rat King player's world by either killing the host or getting to the end of the area, through the fog door. Rat King players can make use of the Pharros' Lockstones given by activating various traps in the Grave of Saints and Doors of Pharros.
Upon joining, the Rat King will grant the player the Crest of the Rat ring. In order to gain ranks in the covenant, Rat Tails must be offered to the Rat King:
|Rank||Rat Tails Offered||Rewards|
|-||0||Crest of the Rat|
|+1||10||10 Small Smooth & Silky Stones|
|+2||20||10 Smooth & Silky Stones|
|+3||35||Slumbering Dragoncrest Ring|
- Members of the Rat King covenant must wear the Crest of the Rat in either the Doors of Pharros or Grave of Saints to summon other players into their world.
- All enemies in both areas are affected by bonfire intensity. This effect stays even after joining the Rat King covenant, making it considerably harder for summoned players to beat hosts with higher bonfire intensities.
| Bell Keepers • Blue Sentinels • Brotherhood of Blood • Company of Champions |
Dragon Remnants • Heirs of the Sun • Pilgrims of Dark • Rat King • Way of Blue