Everyone's favorite trasher, trashing bad cards and turning them into good cards. If you are the only one trashing 2 different cards, you can get a $4, which is pretty good. If someone trashes something you aren't trashing, you can even get a $5 or a $6.
I trashed a silver once in trying to get a $5, and my opponent trashed nothing, so I had to settle for a $4, which was sad.
It gives a major benefit for all players on the table, so interaction without an attack, but if you benefit (when someone else plays miner), your opponent might as well get a very good card out of it, so is it worth it? You decide. I have played with it when my opponent trashed nothing, just to make sure I didn't get a good card, but maybe that wasn't optimal on his behalf.
But, like all civilization cards, you probably don't want 5 of these, but it's a pretty good card to start your deck with.
Shout out to Cookielord for the flashmechanic; a world of possibilities opens up there.