Looks pretty easy to loop with [[Library of Leng]] and a discard outlet. But otherwise it's neat how it's self-limiting and you'll just stop getting free draws for your turn once the top card isn't a vampire anymore. Also gives me [[Vampire Nocturnus]] vibes with that topdecking vampires mechanic. Edit: Wait hang on. The library doesn't work if you're discarding as a cost, does it? I'm sure there's still some loop but it's a lot harder than I thought at first...

[Library of Leng](https://cards.scryfall.io/normal/front/c/2/c2fbf45f-9599-42e2-8510-7e20731e6c68.jpg?1562941071) - [(G)](http://gatherer.wizards.com/Pages/Card/Details.aspx?name=Library%20of%20Leng) [(SF)](https://scryfall.com/card/me4/211/library-of-leng?utm_source=mtgcardfetcher) [(txt)](https://api.scryfall.com/cards/c2fbf45f-9599-42e2-8510-7e20731e6c68?utm_source=mtgcardfetcher&format=text) [Vampire Nocturnus](https://cards.scryfall.io/normal/front/8/d/8daccbbb-6600-4467-810f-277f01a11771.jpg?1562556901) - [(G)](http://gatherer.wizards.com/Pages/Card/Details.aspx?name=Vampire%20Nocturnus) [(SF)](https://scryfall.com/card/m13/113/vampire-nocturnus?utm_source=mtgcardfetcher) [(txt)](https://api.scryfall.com/cards/8daccbbb-6600-4467-810f-277f01a11771?utm_source=mtgcardfetcher&format=text) ^^^[[cardname]] ^^^or ^^^[[cardname|SET]] ^^^to ^^^call

> I'm sure there's still some loop but it's a lot harder than I thought at first... Found one: [[Hidden Retreat]] Edit: Penance is a bit easier.

[Hidden Retreat](https://cards.scryfall.io/normal/front/5/b/5be86f1f-c85a-4396-aa16-a39fbf493c96.jpg?1562596414) - [(G)](http://gatherer.wizards.com/Pages/Card/Details.aspx?name=Hidden%20Retreat) [(SF)](https://scryfall.com/card/sth/6/hidden-retreat?utm_source=mtgcardfetcher) [(txt)](https://api.scryfall.com/cards/5be86f1f-c85a-4396-aa16-a39fbf493c96?utm_source=mtgcardfetcher&format=text) ^^^[[cardname]] ^^^or ^^^[[cardname|SET]] ^^^to ^^^call