About: http://webisa.webdatacommons.org/82075250

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	So you pretty much use the rules in the same way as you would for Evocation, but the opposing force will be more variable, i.e. in the example you state, the power in the defending ritual is the target number for the opposing one.
http://www.w3.org/ns/prov#wasQuotedFrom	stackexchange.com