invocation
Concise Oxford English Dictionary © 2008 Oxford University Press:
invocation/ɪnvəˈkeɪʃn/
▶noun the action of invoking.
■ an incantation used to invoke a deity or the supernatural.
■ (in the Christian Church) a form of words introducing a prayer, sermon, etc.
– derivatives
invocatory /ɪnˈvɒkət(ə)ri/ adjective.
invocatory /ɪnˈvɒkət(ə)ri/ adjective.
'invocation' also found in these Oxford entries:

