Bloodsworn Knight's power and toughness are each equal to the number of creature cards in your graveyard.
{1}{B}, Discard a card: Bloodsworn Knight gains indestructible until end of turn. Tap it. (Damage and effects that say "destroy" don't destroy it.)
The effect that makes Bloodsworn Squire indestructible until end of turn continues to apply after it transforms into Bloodsworn Knight.