Soulbond is a very odd mechanic, and one that hasn't been returned to much since it was first printed in the original Innistrad block, but Deadeye Navigator is probably the most iconic of the cards with the mechanic due to the ability to go infinite with some pretty innocent looking cards (plus Dockside Extortionist, but we dont need to worry about that one in Commander anymore!)
Crystal Shard is less powerful, but still a handy card
In fact, it is currently the only PSA 10 version of this card
Theres also a returning Bring a Friend promo card, with other prizes for new players
Beacon of Creation Blanchwood Armor Dairy Cow (playtest) Flourishing Bloom-Kin Fruition Howl of the Night Pack Jarad, Golgari Lich Lord Jyoti, Moag Ancient Knight of the Reliquary Last Stand Nissa, Ascended Animist Primal Bellow Rofellos, Llanowar Emissary Sapling Nursery Sylvan Primordial Tangle Golem Timbermaw Larva Waiting in the Weeds Withering Gaze