Originally Posted by
Wildeybeast
The rules aren't incompatible. The Tomb Kings rule asks you take a leadership test on 3 dice and add the result together. However Cold Blooded states that you take a leadership on 3 dice and discard the lowest. So you are forced to take a leadership test on 3 dice (which CB lets you do anyway). However the discard one die then kicks in.
The rules as quoted here (and I must admit I haven't read them) state that you 'add the results together' not 'add the three dice together'. This means that you add the final results of the dice roll, so you would include for example any re-rolls granted by another spell, item etc. So in this case you remove the lowest die, as per the lizardmen special rules and add the 2 dice together, along with any other modifiers you might have.