Iccha-shakti is a Sanskrit term translating to "will-power". It is used as a technical subdivision of Shakti in Shaktism.
Helena Petrona Blavatsky in her The Secret Doctrine (1888) also introduces the concept of "Itcha Shakti":
"Its most ordinary manifestation is the generation of certain nerve currents which set in motion such muscles as are required for the accomplishment of the desired object".References
Iccha-shakti Wikipedia(Text) CC BY-SA