Righty, time to take a look at the characters. As usual, I am not here to offend anyone but I am revewing the list with my 'opponent goggles'.
You've already noted my view on the magical nature I'm sure but a short recap. Magic levels + rituals + books and items + bound items = Abit heavy, especially when you consider the powerful lore and bound items in the list(some are infact game winners).
The Zenith Lord: Skip the rituals for this one. He's incredibly tough, deadly, adds alot of to any unit he joins. Terror is nothing to be laughed at either. Fear would have been enough for him. I think he would add abit too much to a unit while be inherantly deadly(even without magic items). He's tough, 2+ save in hth, killing blow.
For instance; Zenith lord with a unit of Cultists with flails. Let's say 24 strong. Add in swarm banner. What I want to emphasis on here is the ease to get a very powerful synergy effect. Unbreakable infantry, tough lord, it will always march on and punishes your opponent for engaging it with more units(due to the banner).
It is all just a little bit too easy. I also wonder why core units have 40pts banners available too them? The argument that they're costly doesn't quite work for me as they're not bad banners either. If you want to be more deathstar-ish, just give them the range banner. I think we need a few 25pts banners to warrant core units with magic banners.
The Revenant: This is the unit I think I have the most trouble with by far. It is very deadly, terror, hatred, ethereal, unseen death, magical aura, casts 2 rituals, 4+ ward save, 100pts of magic items. It doesn't need to choose armour or protection, you've already given it for 'free' and a Great Weapon is probably your best bet. So the 100pts are perfect to put your scrolls at so the MPs can focus on power dice, the mantle of ritual mastery is an obvious choice for him as well.This character will make your opponent cry, as even with magic attacks it is similiar to a very tough fighter lord. You will want to have a minimum of 2 MPs when selecting this lord character.
My suggestion here would be; Drop the ward save and make it so he contributes +1 PD per turn for any wizard in the same unit(so it is possible to have several wizards with him). This would make him more 'ethereal' and also more restrained in how he contributes to the magic phase.
Reaper: Abit of 'too much at once' here too. I'd ditch the extra weapon options. KB on the hit roll is powerful and 'assassin'-like enough. Definitely skip the re-rolls here too. Not sure about magic items here either. Being Ethereal and all I supposed he'd just drop em
Zenith Prince: Probably skip the full plate here, heavy is more befitting his rank.
Some general thoughts; There are abit too many re-rolls, hatred, special 'special rules' and positive modifiers. It all just tend to stack abit to easily and too quickly.