Priests

[Trumanator]

FYI there is no way except through prophetizing or a unique artifact to increase your priest's H lvl on the strat map. The above mentioned ways are only applicable in battle. The Crystal Shield is especially useful if your priest is only a priest, with no other magic. Then you can spam whatever H spells you want since they don't cost fatigue. The usual weakness of the Crystal Shield is its ridiculous enc.