Elder Entity N'tss X LIGHT Level 4 [ Fairy / FusionEffect ] ATK 2500 DEF 1200 1 Synchro Monster + 1 Xyz Monster Must be Special Summoned (from your Extra Deck) by sending the above cards you control to the GY
I think he'd drawn a second copy of a legendary creature he had on the battlefield one too many times, so he did what Magic designers do and designed something you could use in that situation
For example, you can collect special illustration rares, illustration rares, gold cards, holos, reverse holos, full art trainers, EX cards, etc
It can deal 50 damage for a single Fighting Energy, which one-shots every non-ex version of Eevee by hitting their Fighting weakness, and Rare Candy allows it to come down before Eevee gets to evolve when going first
You can earn resources, cosmetics, and even a secret card - the Genetic Apex Immersive Rare a1-283-mew