There is some ambiguity in the action of various cards that allow you to perform the actions of others cards in play, so I thought it might be useful to summarize the various threads on the subject. (Please correct me if I get anything wrong or leave anything out)
As I understand it, there are two ways that this can happen:
If a card activates another card, any location (or card) specific effects happen at the activated card's location (or to the activated card).
If a card copies the text of another card, any location (or card) specific effects happen at the card's location (or to the card) where the die was actually placed.
Scaenicus copies the text of any of your other character cards in play.
(so, for example, if you use Scaenicus to use Nero's ability, you discard Scaenicus)
Maecenas activates any of your other cards in play, but to do so, you need to pay the cost of playing the card (and any other associated costs).
(so, for example, if you use Maecenas to activate Statua Jovis, you would need to pay 19 sestertii)
Magister copies the text of the card opposite it. If that card is an always active card (like the tuba), then activating the Magister gives you that ability for the rest of your turn.
Via Cassia activates one of your cards directly adjacent to it.