Karissa, Iron Heart Engineer

Salvage (Each tapped artifact you control reduces this
cards casting cost by {1})
During your untap step, you may choose to not
untap any number of artifacts. Create a tapped
1/1 colorless Servo artifact creature token for each creature chosen this way.
{t}, Sacrifice an artifact: Draw X cards, where X
is equal to the sacrificed cards converted
mana cost plus 1.