A Heroic Spirit of the Lancer class. He would no doubt be a Top Servant if he were to appear in SE.RA.PH.
He is a Hero who appeared in the myths surrounding the beginning of ancient Rome, and is credited with helping build the country.
Born to the War God Mars and the beautiful princess Rhea Silvia, he was raised by wolves and went on to become the founding father of the empire.
A divine ancestor of Nero, evidence of him can be seen in this tale when an emotional Nero shouts, “Magna Voluisse Magnum,” the name of his Noble Phantasm.

Fate/EXTELLA material: Encyclopedia of Fate EXTELLA