If you use Castellans like mentioned above then you may find your castellan will be wiped out pretty quick. They have 12 will correct but not 12 fate points. For every combat they fight, they lose 1 will exactly like a Ringwraith.
I tend to use them against rabble funnily enough perhaps with spear support. Their fight and strength values of 5 mean that they almost always win combats and wound something. If you choose to fight against enemy warriors then you will probably not use your will points as fate points as you won't lose as many combats. They can easily kill 65 points worth of models (is that how much they cost?) this way. Place them throughout your line, and maneouver them around enemy heroes.
If you go hero hunting with a Castellan then more often than not you will be on the backfoot, expending 1 will point a turn and not inflicting any damage. Added to that you may need to roll with will for fate and if you fail on your last wound, then any will points left are simply a waste as the model is removed as a casualty. Leave trolls or mass hordes of orcs for taking down enemy heroes
