Activate "Shield & Sword" before attacking, to switch the ATK and DEF of your opponent's monsters to Make it easier to destroy your opponent's monsters. "Sphinx Teleia" will actually gain a 500 point ATK boost and your opponent's monster will be significantly weakened.
Keep in mind that this card can be Special Summoned by another card such as "A Hero Emerges".
This card cannot be Special Summoned from the Graveyard.
Note that while you may have two "Sphinx Teleia" and "Andro Sphinx" each on your side of the field, The effect to Special Summon "Theinen the Great Sphinx" is a Spell Speed 1 and so you cannot Special Summon two at the same time.
If you have this card on the field along with "Andro Sphinx", "Levia-Dragon - Daedalus" and "Umi", you can destroy all cards on the field except "Daedalus", including "Andro" and "Teleia" at the same time thus summon "Theinen the Great Sphinx" and having the only 2 cards on the field having in total 6100 ATK.
Using the above strategy, if you pay 500 life points after you summon "Theinen the Great Sphinx", will result in an OTK.