Dark Valkyria

"This card is treated as a Normal Monster while face-up on the field or in the Graveyard. While this card is face-up on the field, you can Normal Summon it to have it be treated as an Effect Monster with this effect: One time only, you can place 1 Spell Counter on this card. This card gains 300 ATK for each Spell Counter on it. You can remove 1 Spell Counter from this card to destroy 1 monster on the field."