Dark champions of Necropolis.

Here, I've reworked it. I fixed the tests, removed the overpowered ability of the Spectral Riders, gave them 175 HP, the damage remained the same, and the defense increased from 27 to 30, plus they now have an attack that causes fear. Also, here's a version with minimal changes to the mechanics (I only adjusted the non-upgradable version, as their flying behavior was awkward).