D/D/D Dragon King Pendragon [YS15-ENL00] Secret Rare

If this card is in your hand: You can Tribute 1 Dragon-Type monster and 1 other Fiend-Type monster from your hand and/or your side of the field; Special Summon this card. Once per turn: You can discard 1 card; this card gains 500 ATK, then you can destroy 1 Spell/Trap Card on the field. This ATK increase lasts until the end of this turn.