Every time you dupe a champion, you get a significant amount of . This is the primary way high-level players sustain their resource stocks. If you were to sell a champion, you’d lose the ability to "dupe" them later, cutting off your steady supply of ISO. 3. Arena Milestones
If you sold all your 2-Stars a year ago, and a new Variant drops requiring them, you are locked out of exclusive rewards (6-Star shards, Tier 5 Basic catalysts) until you grind to get those champions back from scratch. how to sell champions on marvel contest of champions