Fixed

Venomous hydras can currently be recruited nowhere

If the Venomous hydra is intended to be the most common type of hydra, as is stated in the unit description, it probably shouldn't be cap only, as right now it is the least common, since the others can be recruited from every unforted temple of the appropriate type and it remains cap only. I don't think it will hugely change the balance, since they are gold expensive enough that you probably cannot recruit many per turn and they are probably the weakest of the three hydra types.