Klat

The problem I found with petrifex is not that is much stronger than the other legions (it is), but that the other legions feel... wrong, and it isn't by comparison, petrifex is that strong because the battle trait and command ability, and the reason the other legions feel wrong are the command traits and artifacts. All of our generic heroes are support, even the Liege-Kavalos is taken for the RD points and CA, so you don't want combat focused command traits or artifacts, and the only ones that aren't combat focused are the Petrifex and Mortis Praetorians command traits and the Petrifex Artifact (and the Stalliarch Lords if you don't take an artifact in a Liege-Kavalos). And even if we ignore that except Petrifex and Crematorians the others have extra problems in how they feel: Mortis Praetorians have the feel that you have to take named characters Null Myriad have the feelthat you will completely shut yout opponent (against heavy magic list) or that you will be playing without legion Stalliarch Lords feel cavalry oriented, but there is only one cavalry unit, and the batallion already gives that CA so the utility of Stalliarch is for... Nagash? Ivory Host is just bad

With Mortal Contract I think a charging Maw-Krusha doesn't get any damage, Mortal Cotract says attack that inflicted damage, so the Maw-Krusha shouldn't be receiving the D3 in the charge phase, only in the Combat Phase

If Katakros isn't the general he only generates 2 RD points and can't use Supreme Lord of the Bonereaper Legions

I didn't find it particularly hard

yep, if you are playing with vanguard rules (1000 points) you will need to drop a behemoth

remember that Arkhan, as a special character, cannot have the command trait and artifact

White primer. Then Vallejo German Grey for the black areas followed by Nuln Oil (except the shield emblem), Whitee in the recesses i want in green and correcting the mistakes with the grey. After that the white is just a wash of seraphim sepia and an outline of white and in the receses Vallejo Emerald Green. Then with the German Grey I correct the mistakes in the emblem, and the ones in the knees with Eshin Grey, and do the black outlines with Vallejo Dark Sea Grey. Lastly the sword starts with a wash of my own mixture of water, lahmian medium and emerald green that I use for my Nighthaunts and skeletons, but most likely Aethermatic Blue/Akhelian Green/Terradon Turquoise can work similar, then Vallejo Yellow Fluor in the edge, and finally another wash of the same mixture.

My try of the dark scheme

The range of endless spells cannot be increased.