Lancelot, the Graven Knight

First strike, vigilance, protection from white
At the beginning of your end step, you lose 2 life
and may discard a card. If you do, draw a card.
{2}{b}, {t}: Target player reveals his or hand.
You choose a nonland card from it. That player
discards that card. If it wasn't a creature card,
each player sacrifices a creature. Activate this
ability only any time you could cast a
sorcery.