Oil of Armor Animation

Potion, rare

You can spend 1 minute applying this oil to a full suit of plate armor. When you do, the armor animates and is under your control, using the statistics for an animated armor. The armor follows your verbal instructions to the best of its ability (no action required by you); you decide what action it will take and where it will move during its next turn, or you can issue a general command, such as to guard a particular chamber or corridor. If you issue no commands, the armor only defends itself against hostile creatures. Once given an order, the armor continues to follow it until its task is complete. The armor remains under your control until it's reduced to 0 hit points or until it falls unconscious due to a dispel magic spell, at which point it is no longer animated.

Long ago, a trickster came to the court promising the secret to true loyalty. To prove his worth to the king, he revealed a conspiracy against the crown within its own guard. Before the executed conspirators' blood had even cooled, he stripped their armor and carefully oiled it to a sickly shine.
The shining armor rose to take its place at the king's side, where it remained without rest, food, or comfort. In time, the king demanded more, and with each demand the trickster found new traitors to root out and replace. The king eventually came to accept any flaw as betrayal.
With each passing day, another seat was left empty in the guards' mess, and another sack of gold was left in the trickster's coffers. Those who spoke out wouldn't live to see their armor walking patrol the next day.
Until all that remained was the king—mad—and a trickster's army.