I just got this idea, after reminding myself, how in TF2 there used to be major updates, with 2 rival classes dueling each other.
How it would go in DB? Well, 2 similar mercs fight each other, and depending on which side you choose and play more, each merc would grant access to exclusive skin (just no competition for 1 reward, you remember how ReV event went, didn’t you?).
Examples:
Sniper Wars- Vassili vs Aimee
Swagger Duel- Kira vs Phantom
Explosive Spammers Dookie Tennis- Fletcher vs Fragger
Surgeon Massacre- Phoenix vs Sawbones