Does Glissa, the Traitor trigger if a creature dies during your opponent's turn?

Glissa, the Traitor reads: 'Whenever a creature an opponent controls dies, you may return target artifact card from your graveyard to your hand.' This is a triggered ability that watches for a specific event — an opponent's creature dying — with no restriction on when during the game that event occurs.

Under CR 603.1, triggered abilities trigger whenever their trigger event occurs, at any point during the game, unless the ability specifically restricts timing. Glissa's ability contains no such restriction, so it triggers on any turn — yours, your opponent's, or even a third player's in a multiplayer game.

The trigger goes on the stack the next time a player would receive priority after the triggering event (CR 603.3). So if an opponent's creature dies during their combat phase on their turn, Glissa's ability will trigger and be placed on the stack, letting you return an artifact card from your graveyard to your hand.

Concrete example: It's your opponent's turn and they attack you with a 2/2. You block with a 2/2 token, and both creatures die. Glissa's ability triggers from the opponent's creature dying, goes on the stack after combat damage resolves, and you may return an artifact card from your graveyard to your hand — even though it's not your turn.

Note that Glissa herself does not need to have dealt combat damage or be involved in the combat at all; her ability simply watches for any opponent-controlled creature to die (CR 603.1, 700.4).