If you want to connect with the guillotine god, you should first read his writings. Even if they are not related to anything you need to know, books and words hold the vibrations of the people that hold them. Robespierre especially was someone drawn to revolution and spirituality later in life, as we see when he founded the church of the supreme being. If you read his documents he obviously did not live in a time period where socialism was an option, but he had a similar thought process to us who are socialists. He was able to realize that in a society where a republic system of government was the best for the masses, those who would scheme or collaborate with the nobility are enemies of the people who will create death and suffering for anyone who wants freedom. These people are doing things that go against our own self-preservation and it should be understood as such. Just how we can understand that with socialism today, he was able to apply it with his own system that made sense for his own era in time. Invoking him creates revolutionary sentiment in your community, but it’s very extreme with him and it is not necessarily associated with any specific ideology so it must be used carefully.
The Guillotine God can be called upon by sending a shikigami to go talk to him, but the easier way of doing it is simply to call upon the committee of public safety which still exists in the underworld, and requesting aid to your part of the land of the living. find a calm space to meditate and say “Oh committee of public safety, we live now in an era where tyrants are not the feudal nobles but are the wealthy bourgeoisie who exploit and oppress our people. Please send the guillotine god Robespierre to clean up society of tyrants as he sees fit.” as you say these words, you will feel shifts in energy that will confirm your petition has reached them. Go on as you normally would, and watch the masses to see what they do next.