Mortis was a planet enclosed in a monolith located in the remote Chrelythiumn system that was a conduit for the entire Force of the universe. Mortis became home to the Ones, a family of powerful Force users, years prior to the Clone Wars.
Star Wars worlds → The Jedi Temple, Coruscant
“Do what must be done, Lord Vader. Do not hesitate; show no mercy.”
“You were right about me.”
‘What should he be afraid of?
Except…fear lives inside him anyway, chewing away the firewalls around his heart.’
Luke Skywalker» Star Wars Episode V: The Empire Strikes Back