MediaServerStop
Stops playback on the specified/assumed/elicited player.
Reminder: It's 'Alexa, tell MediaServer to Stop' and not 'Alexa, Stop'.
Invocation options (choose based on grammar-fit):
Alexa, [ open / start / launch ] MediaServer
Alexa, [ ask / tell ] MediaServer [ to / for ] …
stop playback
stop {Player}
stop the {Player}
stop the {Player} player
stop playback in {Player}
stop playback on {Player}
stop playback in the {Player}
stop playback on the {Player}
stop playback for the {Player}
stop playback on {Player} player
stop playback on the {Player} player
stop playback for the {Player} player
