When an opponent takes control of your unit (e.g., with Possession) and that unit dies, who gets the Deathknell effect - the original owner or the player who controlled it when it died?

Ruling: The player who controlled the unit when it died gets the Deathknell effect and controls the trigger, even though the card goes to the original owner's trash.

Sequence:

• Unit dies while under opponent's control
• Card goes to original owner's trash
• Deathknell trigger is controlled by the player who controlled the unit when it died
• That player resolves the Deathknell effect

Nuances:

• Control only exists for objects on the board; players do not control cards in non-board zones like trash
• Deathknell triggers during the process of being sent to trash, looking back to the last controller on the board
• Cards that recycle always go to the owner's deck, not the controller's deck