(Look at the top X cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.) Once Lydia Frye has been blocked, increasing the blocking creature's power to 3 or greater won't cause Lydia Frye to become unblocked
It just so happens that the card is part of a subset of cards with their own set symbol and three letter code: Ragavan, Nimble Pilferer
It's got flash, it counters a critter or artifact on arrival, and it's great
They are my favorite Ultimate Guard products, and I wholeheartedly recommend them to all card game players!
Before 2017, the only card that incentivized a Cat deck was Raksha Golden Cub and Kemba, Kha Regent if you squint
Bastion Protector keeps Sigarda alive, and Riders of Gavony can make your team unblockable in many scenarios