A much maligned card, and with good reason, since there were very few things that could be done with it 'back in the day'. But, since the release of the Borealis' Thule Subsea: Safety Below, Ontological Dependence, and Mr. Hendrik, inflicting core damage has become a much more enticing prospect. Coupled with the (surprisingly still) legal Riot Suppression and MCA Austerity Policy makes Tempus' trace value a means of keeping the runner's credit balance in check, if not outright helping you score Ontologicals along the way. I've had games where a lone Tempus guarded an Ikawah, because the runner knew stealing it would mean dealing with the tag and bag I had in store for him sooner than he wants. All in all, a useful card in core damage-oriented decks, the ones that hurt the most.