Activate "Shield & Sword" before attacking, to switch the ATK and DEF of your opponent's monsters to inflict more damage (as most monsters in defense mode have high DEF, which is now turned into it's ATK). "Andro Sphinx" will not be affected as much since there is only a 500 point difference in his ATK and DEF, 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.
It can actually be better to use this card without "Theinen the Great Sphinx" or "Sphinx Teleia", as the former lacks any particular gamebreaking effect, while the latter's effect is somewhat redundant ("Teleia" having only average ATK for a 2 tributer, while only dealing effect damage based upon DEF, which most monsters do not have a lot of, or is too strong for "Teleia" to destroy).