If your opponent controls a monster and you control no monsters, you can Special Summon this card (from your hand). You can only Special Summon "Unknown Synchron" once per Duel this way.
NM-Mint 1st Edition - $0.10
Lightly Played 1st Edition - $0.10
Moderately Played 1st Edition - $0.10
Heavily Played 1st Edition - $0.10
Damaged 1st Edition - $0.10
NM-Mint 1st Edition Non English - $0.10
Lightly Played 1st Edition Non English - $0.10
Moderately Played 1st Edition Non English - $0.10
Heavily Played 1st Edition Non English - $0.10
Damaged 1st Edition Non English - $0.10