freyar
Extradimensional Explorer
Ok, most of what we need from the shield guardian will just go in the flavor text (I kind of wonder if we should include something about multiple people using the key word, supposing that PCs might read the owner's thoughts or something):
When it is fashioned, a vault guardian is keyed to a particular magical key word. A creature that tells the vault guardian the key word becomes that vault guardian's master. Typically, the creator of the vault guardian passes the key word to the golem's new owner after construction is completed. A vault guardian obeys its master’s verbal commands to the best of its ability. It can also be keyed to perform specific tasks at specific times or when certain conditions are met.
When it is fashioned, a vault guardian is keyed to a particular magical key word. A creature that tells the vault guardian the key word becomes that vault guardian's master. Typically, the creator of the vault guardian passes the key word to the golem's new owner after construction is completed. A vault guardian obeys its master’s verbal commands to the best of its ability. It can also be keyed to perform specific tasks at specific times or when certain conditions are met.