All face-up monsters on the field become Machine monsters. Machine monsters you control gain 500 ATK/DEF, also Machine monsters your opponent controls lose 500 ATK/DEF. You can banish this card from your GY, then discard 1 card; add 1 EARTH Machine monster from your Deck to your hand. You can only use this effect of «Clockwork Night» once per turn. You can only activate 1 «Clockwork Night» per turn.