text: The ability that triggered will think that it triggered at the normal time and for the normal reason. It may refer to attacking creatures you control, except it’s your opponent’s end step. It may be looking for a card in the graveyard after a dies trigger, but the creature is still sitting on the battlefield. It may be looking for the spell that caused it to trigger, but there was no spell. If the triggered ability can’t determine the information it needs, or if it can’t find the objects it expects to find in certain zones, those parts of the effect just do nothing.