Right now you can already go and see their AI agents battling it out in TPC's specially provided simulator, like some kind of Pokmon-based ant farm
Brushfire Brushfire featured cards in the fire and grass typing, the holographic foil card inside was a Ninetales
Both give fuel to Hiram Flaversham Toymaker who can banish items on play and Questing which allows you to draw two cards
On the other hand cards from Event Decks, Clash Packs and the ones gotten from Prerelease packs are also glossy in similar fashion
It can only be done at sorcery speed, which is fair, but it's so good in Shilgengar, Sire of Famine
Of course, if you can find a way to get rid of the +1/+1 counter that undying gives it, you might be able to get undying to trigger again