Karth Sultai Emissary

As you cast Karth Sultai Emissary, you may
sacrifice any number of permanents. Karth
Sultai Emissary costs X less to cast where X
is the total converted mana cost of the permanent
or permanents sacrificed this way.
Sacrifice a permanent: draw X cards where X is
the permanent's converted mana cost, or return
target permanent with lesser converted mana cost
from a graveyard to the battlefield under your
control.