I'm definitely excited to try Vivien. She seems like the perfect role-player for my mono-green. Incremental card advantage with a coincidental Naturalize tacked on? And that ultimate! I don't know how often I'll get it, but when I do, ho boy! Makes attacking virtually never bad.
Other cards I'm interested in are Colossal Majesty, Elvish Rejuvenator, Gigantosaurus, Goreclaw, Reclamation Sage, and maybe even Aggressive Mammoth. Honestly, there's so many cards in M19 that I won't have any trouble transforming this thing into a Commander deck after the first rotation happens.
Trap your friends in an endless game with this 23-card combo!