Collar of Silence

A Collar of Silence is a magic item that negates the wearer's ability to speak. These collars are carried and used by mage hunter golems.

Description
A creature can attempt to force the collar around the neck of another creature by grappling them. The collar locks around the creature's neck once donned. The collar must then be activated by making an Intelligence (Arcana) check with a DC higher than 15 but lower than 25.

Once activated, the creature wearing the collar is unable to speak. The collar as depicted in Campaign 2 is implied to prevent specifically verbal components of a spell from being spoken, and the statblock of a mage hunter golem in Tal'Dorei Campaign Setting Reborn stats that no spells can be cast. The collar can be unlocked using thieves' tools, but doing so is difficult.

Campaign 2: The Mighty Nein
While exploring the Folding Halls of Halas to rescue Yussa Errenis, the Mighty Nein encountered a mage hunter golem that guards the Halls. The golem could clamp these collars around the necks of intruders to nullify much of their spellcasting abilities, and did so against Caleb. The collar was able to be removed, and he kept it. When the party later found and rescued Yussa Errenis from the prison within the Halls of Halas, he was wearing one of the collars around his neck which Nott was able to remove with a very high lockpicking roll.

Caleb found that the collar was rendered inert after being removed from him, and determined that he would need an arcane cortex from one of the golems of Aeor to recharge it. While exploring one of the ruins in Eiselcross, the party encountered such a golem, and Caleb was able to remove the cortex. After much tinkering and his own failures to successfully insert the gem into the collar, he asked Jester to attempt it and she succeeded.

Caleb later gave the collar to Beau, feeling she had a better chance of being able to successfully place it on Trent Ikithon. When Ikithon confronted the party at the Blooming Grove, Beau managed to grapple the collar onto his his neck. Astrid, turning on her master, then activated the collar after Caleb's attempt to do so failed.

Campaign 3: Bells Hells
Ludinus Da'leth and the Ruby Vanguard used mage hunter golems to secure the Tishtan excavation site in Marquet while they built a Malleus Key there. Caleb was captured trying to sabotage the Key and was restrained by a golem. Imogen Temult successfully used Command to convince it to release him, but doing so left a Collar of Silence around his neck.