Extends the weekly lockout to Kings's rest when you are outside the instance through a button. Another button appears when you are inside the instance to cancel the extended lockout.
This makes it slightly more convenient to farm the "Mummified Raptor Skull"-mount.
https://www.wowhead.com/item=159921/mummified-raptor-skull
Inspired by the following comment from Lliteral on wowhead.