Goat format ruling
Theinen the Great Sphinx
Card effect (current official text)This card cannot be Normal Summoned or Set. This card cannot be Special Summoned except by paying 500 Life Points when both "Andro Sphinx" and "Sphinx Teleia" on your side of the field are destroyed at the same time; then you can Special Summon this monster from your hand or Deck. When this card is Special Summoned, by paying 500 Life Points, increase the ATK of this card by 3000 points until the end of the End Phase.
Rulings
- When you Special Summon Theinen the Great Sphinx you do not have to pay the additional 500 LP to increase its ATK, you can choose to leave the ATK at 3500. If you do not pay the extra 500 when it is Summoned, you cannot later decide to pay and increase its ATK, it must be done when it is Special Summoned.
- The effect of Summoning Theinen the Great Sphinx is a Trigger Effect, so you may do it during your opponent’s turn if Andro Sphinx and Sphinx Teleia are destroyed simultaneously.
- Since Summoning Theinen the Great Sphinx is a Spell Speed 1 effect (Trigger Effect), you cannot chain multiple Special Summons of Theinen the Great Sphinx to one another. This means you can only Special Summon 1 copy of Theinen the Great Sphinx when the conditions are correct. You CANNOT pay 1000 LP to Special Summon 2 copies of this card.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Goat forum — sourced change requests get reviewed.