Shadowverse

Ah, judging by versatility, I agree with you about the Sabre, Bafich, and maybe even the Ferver. But I was talking about their importance for a specific deck. Without Belfigor, there wouldn't be Blood Vengeance; without Ozzy, Filth wouldn't be so overpowered, and so on.

Catacombs and Orpheus carried Aggro until the Balance Lord took control of the Craft.

Even before all these guys appeared, Aggro was doing great with the combination of Howl + Koko + Mimi, as far as I remember.

Many still consider Khavy to be one of the "legendary-tier silvers," but he shone in Necropolis, and Necropolis shone for a short time, unfortunately.

Yeah, during the recent second coming of Mid-Shadow, many also tried to use him, although he wasn't playing such an important role anymore. Also, in Haven, there's a class card for the Priest with a very similar mechanic, and it's an Epic (= Gold).