Quicksmith Rebel

• WWizards of the Coast2017-02-09
  Official Ruling
  If Quicksmith Rebel leaves the battlefield while its ability is on the stack, the artifact never gains the damage-dealing ability.
• WWizards of the Coast2017-02-09
  Official Ruling
  If another player gains control of Quicksmith Rebel, the artifact will no longer have the damage-dealing ability, even if you regain control of Quicksmith Rebel.
• WWizards of the Coast2017-02-09
  Official Ruling
  If Quicksmith Rebel leaves the battlefield, you no longer control it.
• WWizards of the Coast2017-02-09
  Official Ruling
  If Quicksmith Rebel or the artifact leaves the battlefield while the damage-dealing ability is on the stack, that ability resolves as normal.

Rulings via Scryfall