Phyrexian Duelist

Infect (This creature deals damage to
creatures in the form of -1/-1 counters and
to players in the form of poison counters.)
When Phyrexian Duelist attacks, the defending
player may pay {p/b}{p/b} or Phyrexian Duelist
cannot be blocked until the end of turn.
Discard a card, {p/b}: Phyrexian Duelist gains
Shroud until the end of turn.