Well it means that a level 20 summoner with Undead Queen (So CR 16 undead) would be able to call a bone creature wizard. This wizard can now have any selection of feats or spells its really wants giving the character insanely valuable list of practically every spell in existence. I think that might be a bit too strong.

Also another thing, do the creatures you summon with undead queen have items? If so do they have NPC wealth or PC wealth? And if they do thats another thing that might be a bit too strong as you could summon an bone creature rogue or something that has a large list of scrolls or other consumables to get at will consumables.

If you can summon class levels it just allows too much customization and flexibility to be balanced IMHO.


Also for eternity pact, I think I have the general idea you wanted for this ability but I think its too strong at the moment. For these reasons.

At high levels its pretty easy to get immunity to death effects/pump saves high enough that damage is the most reliable way to kill you.
Undead are naturally immune and can't be knocked out (Minimum HP is 1 not -9)
Diehard lets you act while at -9 and thus you can't really stop the character.

Frankly something similar to the Kingdom of Forever ability (Also bump up the prereqs similarly)