Activate this card if both players have 5 or more monsters in their GYs; destroy as many monsters on the field as possible, then each player banishes (face-down) all monsters from their Deck, then you can Special Summon 1 Normal Monster from your GY.
Once per turn, during the Standby Phase: Activate this effect; each player can Special Summon 1 monster from their GY, ignoring its Summoning conditions, but banish it when it leaves the field.
You can only activate 1 "Underworld Circle" per Duel.