From the Malifaux Tactica Wiki:
The Exorcist is a minion for the Guild.
With a walk of 3” and no charge the Exorcist is one of the slowest Guild models. To get around this the Exorcist has a zero action Driven by Purpose which makes the model suffer one wound and pushes it 3”.
With only 7 wounds and a lack of healing in the Guild Faction, the Exorcist will not make much use of this action but it is useful for positioning him or pushing him out of melee range.
The Exorcist is armed with a Sanctified Crossbow. This weapon has range of 10” and is Magical. Like most Guild models it has Critical Strike built in, giving the weapon a nice damage profile of 3/4/5 with the abilities to get to 4/5/6. With a CB of 5 the Exorcist is likely to hit most minions.
The Exorcist enables Lady Justice to deal full damage against Spirits by granting her already impressive Greatsword Magical. Combined with that and Blind Justice to ignore Pitiful and Harmless, she can shore up her weakness against Kirai with this minion.