User blog comment:Degritone/Wowser, the Graveyard Spectre/@comment-26186030-20150610154912/@comment-25364408-20150610155542

In my mind, it would be T, but it could be a number, the tilde, middle click, or any amount of things. If it DID get its own button, like T, they could also move champion-specific interactions (Kalista comes to mind as I write this) to it (rather than an item slot in Kalista's case) and just have a pop-up that says "Hey, T *does a thing*" at the start of the game so the newbies know that it does thing. There would also be a number on the passive when it's ready to go.