This list is of cards that I've seen and played in my own games this year
At the beginning of your end step, if eight or more cards are in your graveyard, transform this enchantment
You gain the ability to more easily play cards with lots of black pips like Necropolis Regent and Vampire Nocturnus, or even Cordial Vampire and Captivating Vampire
It featured in some of the earliest decks in the game, it was a pivotal piece of the Sligh deck which essentially acted as the foundation of the mono red aggro archetype, and its presence has been significant in Modern from the first day of the format as it has featured in many of the formats best decks from Zoo to Splinter Twin to Jund
If mana generated with Arena of Glory's last ability is spent on a noncreature spell that becomes a creature later in the turn, that creature won't have haste
Cards like Star of Extinction and Blasphemous Act gain 80-100 life with this pair