Duelist's Moor

{3}, {t}, Sacrifice a creature: Each opponent sacrifices a creature, then draw a card.
{t}: add {b}{b}. Activate only if you have seven or
more creatures in your graveyard.
{5}: Until end of turn, Duelist's Moor becomes a
1/1 black Horror creature with deathtouch, indestructible and: whenever you draw a card,
each opponent sacrifices a permanent.
Duelist's moor can be your commander.