Edison format ruling
Theinen the Great Sphinx
Card text as printed in this era© Can't be Normal Summoned/Set.
© Must be Special Summoned by its own effect.
① When "Andro Sphinx" and "Sphinx Teleia" you control are destroyed at the same time: You can pay 500 LP; Special Summon this card from your hand/Deck.
② When this card is Special Summoned: You can pay 500 LP; until the End Phase, this card gains 3000 ATK.
Rulings
- The only way you can Special Summon this card is via its trigger effect. Even if it was initially summoned that way, you still can't summon it with card effects.
- The effect to summon this card is a Trigger effect. It can activate while in the hand or Deck. You can't activate the effects of 2 or more of this card's effect in the same Chain, so you can only Summon 1 "Thenien the Great Sphinx" at a time.
- Both of this card's effects are optional, and both can can miss their timing.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Edison forum — sourced change requests get reviewed.