"Necropolis" - changes to creatures of levels 6-7.

Sometimes, in some multiplayer games, knights would appear (though rarely), and it seems to me that a dead dragon shouldn't be stronger than a living one. They could be made into creatures of level 6, with "Horrific Presence" for the spectral one, "Etherealness" for the astral one, and 100 HP each, with one of them having "Death Strike" and the other having some kind of "Sorrow Strikes," and slightly higher stats.
For the Herald, give it "Attack with Fear" and 200 HP instead of "Presence" and 155 HP.