Because DEY SO GLOSSEH!!!~
Also, 100 x # of Glossy cards played in the Duel. So, easy Math, 10 Glossy cards were played or Activated.
Markosipo 6days ago
"Victory by Effect Damage Only" can be also obtained by doing damage only with effects and winning the duel by a Deck Out Victory. In other words, you can use a Raimei and win by Deck Out without causing battle damage and you'll get a "Victory by Effect Damage Only" reward.
Monsters that are special summoned through another card effect don't get the assesment points "played a Glossy or Prismatic". That means Glossy or Prismatic Fusion and Ritual Monsters dont get assessment points.
My reddit thread: https://www.reddit.com/r/DuelLinks/comments/62l68t/clarification_comeback_victory_for_level_57_40x/
How to Trigger the "Comeback Victory" in Duel Links?
At the beginning of the turn that you finish your enemy you have to have less HP than the enemy.
Example: You have 2K HP and Your Enemy has 3K HP. You deal 3K Damage and finish him off. You will receive the Comeback Victory Bonus.
What are possible Opportunities to get it?
Ceberus is the most Common deck. Get attacked, Sorcery Conduit or Low Level Draw as Skill, You draw Ceberus and Power him up to finish enemy.
Are there faster Versions to get 40x for Level 57?
In my opinion, the fastest way is using Wrecker Panda
Build a deck with 1-3x Wrecker Panda Use Skill "Earth Draw" or "Low Level Draw" Put ONLY Monsters in the Deck (as many high Level as you have) Summoner Wrecker Panda, Use it's skill to finish off enemy with one turn.