Sphinx

They are good melee units, perfect counter against groups of archer units.They have 2 upgrades which are a must-have if you plan to use them en-masse.(Classical Age).Even one is great to counter enemy archer rushes but if you have like 5+, which is recommended and upgraded as well, no ranged unit or building can stop them, except, of course, heroes and high-end myth units, like Medusa or Petsuchos.

Upgrades
Criosphinx

Hierosphinx