Miz appears as a non-hostile enemy when the mission is accepted, and two interaction options appear at close range: "Shop" and "Punch" (punch being a regular melee attack). Shopping opens a conventional med vendor interface with only the Mysterious Amulet offered at an exorbitant price. Buying the amulet or attacking Mr. Miz completes the mission.
"You have chosen quasi-wisely."
Turn in: Mr. Miz
The mission's availability is contingent on Mr. Miz appearing, which is an occasional event.
If the mission is completed via punching Mr. Miz, the ability to purchase the Mysterious Amulet is lost until a further playthrough.
In multiplayer, only one player may purchase the amulet.