The help came from the Rose Cross Society, a secret society established in Germany at the beginning of the 17th century, attributed to Rosenkreutz from the 15th century. The name of the society might have been derived from their emblem of a rose on a cross.
However, in their outward propaganda, the Rose Cross Society claimed to have been founded in 46 CE when a disciple of Jesus, Marco, successfully converted Ormus, a Gnostic philosopher from Alexandria Port, along with six of his followers.
The Rose Cross Society was born from these conversions, integrating Early Christianity and Egyptian mysticism to form a secret society connected with superhuman knowledge and involved in the pursuit of various magical practices.
Unlike the Europe-centric Golden Dawn, the core skills of the Rose Cross Society are focused on alchemy, which is why Leonard Ethan had more interactions with them previously.