In this guide, I got over how to steal any relic off of another empire when you land on their capital. There is a 5% chance that normal empires take a single relic when you occupy their capital, and you do not get to choose which relic you steal.
There is a 5% chance that a normal empire takes a single relic when they occupy their enemies capital, and they do not get to choose which relic they steal. Barbaric Despoilers have a 10% chance to seize a relic when they land on their enemies capital.
If you can wipe out the enemy empire, then a dig site with their relics will appear on their old capital.
New MP Meta
You can check victory score for relics to pick war targets in competitive mps
I think you should be able to trade relics, as they can go between players in “wars” to transfer them. A trade is more fair, as an aggressor could break their word against a helpful player wouldn’t be an issue in the mps I host)
Maybe not an option because you could cheese cooldowns on relics/ maybe be hard to program so that the cooldown is galaxy wide instead of just within an empire.