As you play through Ember Knights, you’ll eventually come across these black orbs called Relic Orbs. They serve no purpose during your playthrough of the areas, instead, you’ll need to speak to Esper to learn more about them.
What do Relic Orbs do in Ember Knights?
You need to talk to Esper the next time you die after finding a Relic Orb. He will take it, and a new Relic will be unlocked as a possible find during your gameplay. The first time you turn in a Relic Orb, you are shown how many more monsters you need to kill before you can find another.
It takes a certain number of monsters to drop another Relic Orb. A new Relic is unlocked with every Relic Orb found, and the number of monsters you have to defeat increases. The new Relics are not better than the old ones; they just have different stat bonuses. We would not consider them game-changers in any way.
Collecting Relic Orbs does not add the Relic to your collection as having been discovered. The Relic still has to be picked up before being added to your collection as a discovered Relic.
For more Ember Knights, why not check out How do you revive other players in Ember Knights? or When do I unlock the Bow in Ember Knights? here on Pro Game Guides.