Mafia 92. Void Lord.

The Manticore appeared in the computer games of the «Disciples», «Dark Souls», and «Might and Magic» series — in «Heroes of Might and Magic III» and «Might and Magic 7», it looked like a lion with a scorpion's tail and wings (it looks similar in the animated series «My Little Pony» (S01E02)).

Good tea. I should treat Paige and Plant with it and tell them what the name of their favorite cottage, Bron-Yr-Aur, actually means.
The Mortulus clue was generally good at first, but it lacks good feedback if you look at it from the GM's point of view: the GM sees the date, uses it to find the fifth heroes, and then suddenly switches to manticores. Which, by the way, weren't even in the first version of the fifth game (I might be wrong).
The clue for the Master seems to be fine, but I agree that the length of the chain is confusing compared to the old clues from the Sky. The rest, like Greek mythology and the Witcher's bestiary, seems too associative. For now, NNV.