Hey everyone! A few days ago I had a neat idea that I haven't seen yet, and after getting back from vacation finally had an opportunity to give it a go. I give you, Infinite Undatakah Priest.
https://outof.cards/hearthstone/decks/3021-infinite-undatakah
As you can see in the guide, at its core, it's a Control Priest deck, but with a neat ending. The set up for the combo is to play (and have die) Test Subject (or two) and Recurring Villain. Then, once you play Da Undatakah and cast Seance, you go infinite when Da Undatakah dies, and depending on what is in the Deathrattle pool, you either get two Seances or resummon Da Undatakah twice (if you've cast at least one Arms on Recurring Villain).
If you end up with multiple copies of Seance in your loop, you can then also go infinite with Grave Horrors.
Elysianna is there to not die in fatigue.
Flex spots are definitely Elysianna and Madame Lazul, and probably others.
As the guide says, this deck is mostly garbage but it's fun nonetheless. Play it, test it, have fun with it, let me know what you'd change...Enjoy!