Ring of Recruitment is a powerful loot item that is the reward for defeating the Primordial Malevolence.
The Ring of Recruitment is used as part of the Radial Equipment Menu, which is opened by pressing F (by default). It displays any ring equipped onto the player (in red tab) as well as rings in their inventory (in green tab); this ring can be both equipped and 'unquipped' with a left click. This allows for easy management of ring equipping; however, note that only one ring can be applied at a time.
When equipped, it will provide the player with the ability to recruit most mobs they come across, including passive mobs. This can be done by holding right-click on the mob with an empty hand for a certain amount of time (up to six seconds), using special particles that transfer to the mob to indicate it is recruited. When recruited, the mob will fight by the player's side, using its own attacks against non-recruited enemies, while bringing down its original health for balance. Note that when recruiting, charge is depleted from the ring, and should charge be fully depleted, any recruited mobs will no longer be recruited and hostile mobs will proceed to attack the player again. Only one mob may be recruited at a time.
The Ring of Recruitment must be charged when depleted to reuse. This can be done by right-clicking the ring, and it will consume the player's experience to recharge the ring to full power, the amount of experience consumed depending on the amount of the ring's charge that needs to be replenished.