When you defeat an opponent, the game places a weird-looking sigil next to the opponent's portrait:
The colors might be hard to see, but the one to the left is bronze, and the two right ones are silver.
What do they mean? Do the colors represent the opponent's strength? How handily I trounced them? Something else?
Note: this is for Magic: The Gathering: Duels of the Planeswalkers 2012