Kathari Remnant is a uncommon Creature — Bird Skeleton card from The List (PLST), collector number PCA-98. Current market price: $0.28, TCGplayer market prices via Scryfall.
Flying {B}: Regenerate this creature. Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)