Send 1 "Phantom Knights" Spell/Trap from your Deck to the GY.
When an opponent's monster declares a direct attack while you control no cards and this card is in your GY: Special Summon this card in Defense Position as an Effect Monster (Warrior/DARK/Level 4/ATK 300/DEF 600), but banish it when it leaves the field. (This card is NOT treated as a Trap.)
If Summoned this way, this card gains 300 DEF for each "Phantom Knights" Spell/Trap in your GY.