Obadiah, Seeker of Power

Whenever a creature enters the battlefield under
your control, if that creature has power or
toughness greater than Obadiah, Seeker of
Power, sacrifice it, then put an amount of +1/+1 counters equal to its power on Obadiah, Seeker
of Power.
{b}, Sacrifice a creature: Obadiah, Seeker of
Power can't be blocked this turn.