Virtue's Ruin
2B
Sorcery
Text: Destroy all white creatures

I've been slowing picking these up to use as a sideboard card in UB Tendrils. I've been testing in the board as there are several decks in my metagame that run Gaddock Teeg and Ethersworn Canonist. The Canonists are especially annoying because they are used in BW and UW decks which both have Mother of Runes. This has made it difficult to use bounce or spot removal as an answer. I stumbled across this and its been testing well as an answer to these cards.