This is the Nothing card set I came up with in less than an hour. It is not complete.
Name: The Never Swordsman
Card: Monster
Level: 4
Type: Nothingness
Atr: Light
Atk: 1900
Def: 1400
Description: This card's atr is treated as both Light and Darkness at all times. At the end phase of the turn this card is summoned remove it from play and special summon it at your draw phase, but not if you have used this ability on two other Nothingness monsters before it in that same turn..
Name: The Never Sorceror
Card: Monster
Level: 2
Type: Nothingness
Atr: Light
Atk: 1000
Def: 200
Description: This card's atr is treated as both Light and Darkness at all times. At the end phase of the turn this card is summoned remove it from play and special summon it at your draw phase, but not if you have used this ability on two other Nothingness monsters before it in that same turn. When this card is summoned special summon one tuner monster from your deck to the field and increase your life points by 100 for each level it has.
Name: The Western Dragon of Forgotten Souls
Card: Monster
Level: 6
Type: Nothingness
Atr: Light
Atk: 2300
Def: 1600
Description: This card's atr is treated as both Light and Darkness at all times. At the end phase of the turn this card is summoned then remove it from play and special summoned at the draw phase of your next turn, but not if you have used this ability on two other Nothingness monsters before it. When this card is summoned you can send every magic card in your graveyard to your grave. Inflict 500 points of damage to your opponent for each one. When this card is removed from play by its effect then return all magic cards in your grave to your hand.
Name: Eastern Dragon of Lost Memories
Card: Monster
Level: 6
Type: Nothingness
Atr: Light
Atk: 2400
Def: 1500
Description: This card's atr is treated as both Light and Darkness at all times. At the end phase of the turn this card is summoned remove it from play and special summon it at your draw phase, but not if you have used this ability on two other Nothingness monsters before it in that same turn. When this card is summon you can remove all trap cards in your graveyard from play and increase your life points by 400 for each one. When this card is removed from play by its effect then negate this effect when it's summoned.
Name: Eternity Sage
Card: Monster
Type: Nothingness/Tuner
Level: 1
Atr: Light
Atk: 100
Def: 100
Description: This card's atr is treated as both Light and Darkness at all times. At the end phase of the turn this card is summoned remove it from play and special summon it at your draw phase, but not if you have used this ability on two other Nothingness monsters before it in that same turn. You can increase this monster's level by paying 300 life points each level.
Name: Eternal Daemon
Card: Monster
Type: Nothingness
Level: 4
Atr: Light
Atk: 1700
Def: 0
Description: This card's atr is treated as both Light and Darkness at all times. At the end phase of the turn this card is summoned remove it from play and special summon it at your draw phase, but not if you have used this ability on two other Nothingness monsters before it in that same turn. You can special summon this card by removing the top three cards from your deck from play. Increase your lifepoints by 1000 for each Magic and Trap card removed by this effect.
Name: Aetherion, the Power of Nothingness
Card: Spell
Type: Normal
Level:
Atr:
Atk:
Def:
Description: You can activate one of the following effects:
1. If this card is removed from play then increase your lifepoints by 1000.
2. You can special summon one monster from your hand to the field while ignoring summoning conditions, and make that card both a Light and Dark atr monster. When that monster atks then remove it from play and take damage to your life points equal to its atk.
3. Increase the atk of all Light and Dark monsters by 1500. All monsters affected by this card are unaffected by counter traps. Send all monsters affected by this spell to the grave and half your life points.
Name: Endless, the King of Oblivion
Card: Monster
Type: Nothingness
Level: 5
Atr: Light
Atk: 2000
Def: 2000
Description: This card's atr is treated as both Light and Darkness at all times. At the end phase of the turn this card is summoned remove it from play. This card can only be summoned when Aetherion is activated, and only if it is in your hand. When this card is removed from play then add it to your hand at the end phase of your opponent's next turn.
Name: Aetherion Stardust Dragon
Card: Monster
Type: Dragon/Synchro/Effect
Level: 8
Atr: Light
Atk: 2700
Def: 2000
Synchro Requirements: 1 Tuner + Endless, The King of Oblivion
Description: This card's atr is treated as both Light and Darkness at all times. When this card is summoned remove all spell and traps cards in both player's hands from play. This card gains 400 atk and def for each monster removed from play and in your graveyard with Light and Darkness as both their attribute.