Succubus of Avarice

:Sentinel :[Choose a card from your hand, and discard it] When this unit is placed on from hand, you may pay the cost. If you do, choose one of your vanguards that is being attacked, and that unit cannot be hit until end of that battle. (Soul)Darkness (This ability is active if cards have been put into your soul during this turn):[Choose one of your grade 1 or less rear-guards, and retire it] Return this card to your hand.