Emil Vincent Alonzo
Some of the relic cards I have have a yellow frame border such as Rune of Quicksilver and Cloak of Shadows while others such as Burning Horn and Gem of Greed have a grey border frame. I looked through the rulebook and could not find anything that would differentiate owning a yellow border relic and a grey border relic, so is it a coloring error or are the yellow and grey frameworks going to be explained in a future expansion?
The grey boarded cards are relics specific for the "Starfire" boss. There should be a picture of the dragon in the bottom right of the card ( I TOTALLY didnt notice the pic at first) and are used when you are using him as the dungeon boss.
When newer bosses are released, you would switch out the grey boarded relics with the bosses set of relics.