Once per turn: You can reveal a number of "Nekroz" cards in your hand; increase or decrease this card's Level by the number revealed, until the end of this turn. If this card is Tributed by card effect: You can add 1 "Nekroz" monster from your Deck to your hand, except a Ritual Monster. You can only use this effect of "Ariel, Priestess of the Nekroz" once per turn.