الرعب السفلي بَهِيمُوث سبيليو چيست

FLIP: You can target 1 monster on the field; change it to face-up Attack Position if it is in Defense Position, also change its ATK to 0. You can only use this effect of "Subterror Behemoth Speleogeist" once per turn.
When a face-up monster you control is flipped face-down, if you control no face-up monsters: You can Special Summon this card from your hand in Defense Position. Once per turn: You can change this card to face-down Defense Position.