Blackwell Companions, and instalments from similar series, should be initially sized up according to their purpose and audience. Such hefty tomes present themselves first as reference books—as collections of articles by scholarly experts that treat the key methods, topics, historical developments, etc., in the field. Second, each Companion is addressed to students and teachers as a state-of-the-field resource that provides several benefits: a sound picture of the field, assessment of various theories and methods used in the field, a sense of the innovative developments and open questions, and plenty of information to follow up on. Finally, some Companions give primacy to presenting particular developments in a field and arguing for a certain methodological approach over others.
Stiltner, B. "Book Review: Andrew R. Murphy (ed.), The Blackwell Companion to Religion and Violence." Studies in Christian Ethics 26.2 (2013): 249-52. Web.