The Secret of San Tomaso

Almost 1000 years ago, Thomas of Canterbury, together with his faithful squire on a pilgrimage to the holy city, mysteriously disappeared in the mists of the Treviso countryside. The last person who saw them before disappearing was the Grandmaster of the Templar order, found dead a few days later in his room, on the table was found a map of the city full of strange symbols remained undeciphered and a ticket with the written: "Invocationem pronouncing tenebras dissipare". Today it's up to you to solve this mystery, using clues and overcoming the tests, you have the arduous task of finding and uttering the invocation that could destroy the Dark Masters forever.