The Collar of the Guardian exists of a collar and a ring. The ring contains a tiny pocket dimension that the collar is connected to. The collar can only be attuned to a creature with an Intelligence of 4 or less that is no larger than Medium. While wearing the ring the following applies:

• Add your proficiency bonus to the creature's AC, attack rolls, and damage rolls, as well as to any saving throws and skills it is proficient in. Like any creature, it can spend Hit Dice during a short rest to regain hit points.
• The creature takes its turn on your initiative. On your turn, you can verbally command it where to move (no action required by you). You can use your action to verbally command it to take the Attack action. If you don't issue a command, the creature takes the Dodge action. If you have the Extra Attack feature, you can make one weapon attack yourself when you command the beast to take the Attack action.
• You can use a bonus action to command the creature to take the Dash, Disengage, or Help action on its turn.
• If you are incapacitated or absent, the creature acts on its own, focusing on protecting you and itself. The beast never requires your command to use its reaction, such as when making an opportunity attack.
• The creature can use an action while adjacent to the ring to enter the pocket dimension. Should the creature fall to 0 hit points or die outright while within 100 feet of the ring, it is instead transfered to the pocket dimension and can be summoned again with full hit points after a week.

Notes: a creature with Intelligence 4 or less.