After talking to others I think Undeads unstable just makes them seriously unplayable. Thus I have (with the help of others) worked out some changes to unstable.

1# take your current number of undissrupted ranks away from crumble result or just your static com res.
2# If your steadfast half (rounded up) crumble (thats a current thought all over internet)
3# (and this a good one I think) say that all unstable units in combat dont all crumble but the crumble result can be taken from any number of the unstable units in combat (or divided between them)

I like the last one because it means tk and vc can gang up on their enemy and its worth while but alone they are poorer than standard troops.

When it comes to constucts with the last rule, we can either say their (one less crumble effect) is cumulative or say a max of one constucts rule can only be applied per crumble result. Im with the latter because it sounds fairer but still giving us a advantage.

What does everyone think, any other ideas?

Ooh
4# if an unstable unit(s) win combat, they gain wounds equal to how much they win by. (would be cool but I'm 900% sure it won't be implimented)

I have hope for the Unstable rule as GW has changed a whole rule before (see power scroll) and I think these 3(4) rules would allow Undead to actually be decent.

Hehehe well that would be good, but it's very OTT but I think you were trying to be funny (which it was).

What do you think of constructs for number #3? would be good to get some feedback on this...

Well, I like number 3, passed it onto the thread which is, in theory, designing the new Tomb Kings Army Book...

Personally, I'd prefer the idea of -1 wound for each construct unit in there, since how often would you have enough constructs fighting at once for this to be unfair? Of course, people might then end up using many small units to reduce crumble to almost nothing, but then they'd be losing out elsewhere, couldn't use horde rules etc...

Of course you would, I would too ;) but the question is (putting what we would like to one side) is that abit OTT given that we are getting a very good rule-change. Very important to make the rule-change good enough just to balance unstable out not make it a major advantage.

Personally I feel it should work like the fearless rule in 40k, just seems to make more sense.

Theres a far simpler solution

If a Nehekharan Undead unit is Steadfast/stubborn and losses combat, reduce the crumble result by the unmodified leadership of the unit

You could also expand on this further:

A unit of Tomb Guard that is lead by a royal (Prince or King) benifits from the stubborn rule.

Further to this, you can address the issues with constructs by

All Nehekharan Undead units that have the construct rule benifit from the rules for stubborn

This way you wont have to play around with the lore atribute rules for healing constructs, as with this addition, they become fair and balanced, representing how dificult it is to repair them, but how dificult it is to harm them

IMO, this fixes 90% of whats wrong with the book

If you still think healing constructs is to tough after these changes to crumble then add:

If a model with the "stone shaper" rule is within 12" of a construct unit, the construct(s) can benifit from the Nehekharan lore attricbute more than once per magic phase

As for the other 10% of the book that needs addressed
Spears are free upgrades for skittles
Ushabiti wear light armour for 4+ save total
Halbards on Tomb Guardr cost 1 point
Cost of all Nehekharan Spells are all reduced by 2 to cast for standard castings, and 4 the big castings
Warshpinx save is 3+ to account for howdath/mount/crew etc

I try to make own houserules for our gaming groop and also fix the tomb king book.

For me the main problem is that a general fix to the unstable rule also affects vampires. But they can get a hugh amount of models back via magic and we tomb king players only a very little quantity.
I think it's ok that unstable works different on Tomb Kings, but it's hard to figure out which alternativ rules will be ok and not too good or too bad.
Have you tested some of the rules suggestions in this thread?