Ah ha, a MA Pythium question...

[Wish]

they are great in the late game. play pyth with order and growth to make sure you get loads of cash, then give them to a mage with a serpent ring on, and enough gear to cast fog warriors. fog warrior hydras eat through everything.

also my second expansion army usually consists of 10 hydras and that hydra tamer guy you can recruit. put the hydras in groups of 5 up front and the commander in the back scripted to holdx5 and stay behind troops.

I've had this army eat up a knights of the chalice province (with heavy losses, but still.)

it cuts through lesser indes like a hot knife through butter.