Tormented Bosses

Description: Defeating any of the six Tormented Echo bosses for Diablo 4 Items the first time in a season rewards you with a Resplendent Spark.
Method: Each boss requires specific summoning materials that you can obtain through various endgame activities.
Note: You only get one Resplendent Spark per boss per season, making this a non-repeatable source.
Season Chapter Destroyer’s Cache

Description: Complete the final chapter of the Season Journey Challenges to earn a Destroyer’s Cache.
Reward: This cache contains one Resplendent Spark and other resources. You can earn one Resplendent Spark each season by completing these challenges.
Season Reputation Rewards

Description: As you complete season-specific objectives and Diablo 4 Items for sale raise your reputation with a faction, you may earn rewards.
Note: Occasionally, the final reward in the Reputation track includes a cache that contains a Resplendent Spark, but this isn't guaranteed every season.