Feend vor Sembren

A former “Red” Master. An elite magus sent by the Mage’s Association—the Clock Tower. He possesses skill worthy of being chosen to participate in the grand stage of the Great Holy Grail War, but he was put into a trance after drinking the tea that was offered to him. Naturally, he was on his guard and had defensive spells deployed, but it was all rendered meaningless by poison compounded by a Servant.
Perhaps because he ended up shamefully retiring before he even got to fight, the Sembren family gradually began to fall into ruin after this. His only son is currently struggling hard and making strenuous efforts in a certain classroom, though…

Fate/Apocrypha material: Fate/Apocrypha Encylopedia