A special mlp-themed ring, perhaps to honor their bond. The card's info says:
Ring of Light
Activate only by selecting 1 “My Luminous Pony” monster you control. Destroy 1 monster your opponent controls whose ATK is higher than the selected monster’s.
2 years, 5 months ago
25 Jun 2016 20:28 CEST
Full Size: 1f3e79e05a58dabb80708b1101501d59