Medivh's Silver Coin

Medivh's Silver Coin is fished from the fountain in the Eventide district of Dalaran

Use
Required for

Context
Medivh is the last Guardian of Tirisfal. Medivh was born with the soul of Sargeras already inside of him, a taint created from his mother Aegwynn's battle with the avatar of Sargeras. Medivh opened the Dark Portal to Draenor, causing the First War. The events of the war force Khadgar to kill Medivh to stop his dark magic and free Medivh from Sargeras' control.

The book The Last Guardian goes into greater detail about this part of Medivh's life.

Speculation

 * The three ringing tones mentioned by the coin may reference the three 'parts' of Medivh - the power of the Guardian and the influence of Sargeras conflicting with each other, with Medivh himself cast into the background. Seeing as how the coin is thrown in for a wish, all three parts could be "arguing" Medivh's voice being cast down by Sargeras and his powers as the Guardian of Tirisfal.
 * Another possible reference may be Medivh's involvement in the First, Second, and Third Wars. Having been an important factor to the first two and a smaller, more passive, factor in the third, which would lead to the latter being overshadowed by the others.