In a deeply interactive format playing only sorcery speed is annoying, and it also stops a ton of cards such as Cascade spells, Shelldock Island, Instant Madness cards and Bring to Light
Gallery and List of Undying Cards Butcher Ghoul Demonlord of Ashmouth Endling Evernight Shade Flayer of the Hatebound Garbage Elemental (B) Geralf's Messenger Geralf's Mindcrusher Gleeful Arsonist Hancock, Ghoulish Mayor Hound of Griselbrand Howlgeist Mikaeus, the Unhallowed Nardole, Resourceful Cyborg Nearheath Stalker Pyreheart Wolf Relentless Skaabs Sightless Ghoul Stormbound Geist Strangleroot Geist Treacherous Pit-Dweller Vengeful Vampire Vorapede Witch-king, Sky Scourge Young Wolf Note that one version of Garbage Elemental has undying, though this card has six versions that use the same art, so it gets a little messy
You can see a selection of the cards revealed during the panel below, and head to the official site for additional info.
This card doesn't do much over the course of the game, but it's got acceptable stats for the mana value and it has an incredibly potent ETB effect if you can pay the cost