[NTJedi]

The Vine Ogres are a long term investment where you need like 3 or 4 nature mages pumping 2 each turn... after a dozen turns you have a nice meat shield for your different mage armies.

The lamias are good if you need the troops now or if your opponent has lots of priests.

The mandragoras are great since it takes several banishments for one to fall, plus they will put the approaching enemy troops or SC asleep with the attacks. Also they are definitely worth the price if the caster is a high nature level.